Tính bằng cách thuận tiện: 

a) 15,27 - 4,18 - 2,09 = (15,27 - 4,18) - 2,09

                                  = 13,09 - 2,09

                                  = 11

b) 60 - 26,75 - 13,25 = 60 - (26,75 + 13,25)

                                  = 60 - 40

                                  = 20

c) [72,69 + 18,47] - [8,47 + 22,69] = 72,69 + 18,47 - 8,47 - 22,69

                                                      = (72,69 - 22,69) + (18,47 - 8,47)

                                                      = 50 + 10

Chúc học tốt!

Cac ban lam cho minh ti

a)15,27-4,18-2,09

=15,27-(4,18+2,09)

=15,27-6,27

=9

b)60-26,75-13,25

=60-(26,75+13,25)

=60-40

=20

c)38,25-18,25+21,64-11,64+9,93

=(38,25-18,25)+(21,64-11,64)+9,93

=20+10+9,93

=39,93

d)45+52,17-15,28-12,17

=45+(52,17-12,17)-15,28

=45+40-15,28

=69,72

e)(72,69+18,47)-(8,47+22,69)

=72,69+18,47-8,48-22,69

=(72,69-22,69)+(18,47-8,47)

=50+10

=60

bạn hữu đức làm sai ý e

A, 15,27 - 4,18 - 2,09  = 15,27 - ( 4,18 + 2,09 )

                                 = 15,27 - 6,27

                                 = 9

B, 
60-26,75-13,25=60-(26,75+13,25)=60-40=20

C,38,25-18,25+21,64-11,64+9,93=20+10+9,93=39,93

e,(72,69+18,47)-(8,47+22,69)=72,69+18,47-8,47-22,69=72,69-22,69+18,47-8,47=50+10=60

a, 15,27-4,18-2,09                      

=15,27-(4,18+2,09)

=15,27-6,27

=9

a) \(15,27-4,18-2,09\)

\(=11,09-2,09\)

\(=9\)

b) \(60-26,75-13,25\)

\(=60-\left(26,75+13,25\right)\)

\(=60-40\)

\(=20\)

c) \(38,25-18,25+21,64-11,64+9,93\)

\(=\left(38,25-18,25\right)+\left(21,64-11,64\right)+9,93\)

\(=20+10+9,93\)

\(=30+9,93\)

\(=39,93\)

e) \(\left(72,69+18,47\right)-\left(8,47+22,69\right)\)

\(=72,69+18,47-8,47-22,69\)

\(=\left(72,69-22,69\right)+\left(18,47-8,47\right)\)

\(=50+10\)

\(=60\)

Chiều dài của hình chữ nhật là:

\(36\div\dfrac{3}{5}=60\left(cm\right)\)

Sợi dây thép đso dài số mét là:

\(\left(60+36\right)\times2=192\left(cm\right)\)

Đổi: \(192cm=1,92m\)

Đáp số: \(1,92m\)

\(\text{∘ Ans}\)

\(\downarrow\)

`1,`

`a)`

`15,27 - 4,18 - 2,09`

`= (15,27 - 2,09) - 4,18`

`= 13,18 - 4,18`

`= 9`

`b)`

`60 - 26,75 - 13,25`

`= 60 - (26,75 + 13,25)`

`= 60 - 40 = 20`

`c)`

`38,25 - 18,25 + 21,64 - 11,64 + 9,93`

`= (38,25 - 18,25) + (21,64 - 11,64) + 9,93`

`= 20 + 10 + 9,93`

`= 30 - 9,93`

`=``20,07`

`e)`

`(72,69 + 18,47 ) - (8,47 + 22,69)`

`= 72,69 + 18,47 - 8,47 - 22,69`

`= (72,69 - 22,69) + (18,47 - 8,47)`

`= 50 + 10 = 60`

`2,`

Chiều dài của HCN đó là:

`36 \div \dfrac{3}{5} = 60 (cm)`

Đổi `60 cm = 0,6 m`; `36 cm = 0,36 m`

Sợi dây thép dài số m là:

`(0,6 + 0,36) \times 2 = 1,92 (m)`

Đáp số: `1,92m.`

Bài 2:a)\(\left(99,5-x\right)+3,82=30\)

\(99,5-x=30+3,82=33,82\)

\(x=99,5-33,82=65,68\)

b)\(x+37,66=80,94\)

\(x=80,94-37,66=43,28\)

c)\(76,22-x=38,08\)

\(x=76,22-38,08=38,14\)

d)\(36,7-x=21,205\)

\(x=36,7-21,205=15,495\)

e)\(x+17,67=100-63,2\)

\(x+17,67=36,8\)

\(x=36,8-17,67=19,13\)

Bài 3:

a)\(15,27-4,13-1,14\)

\(=\)\(15,27-1,14-4,13\)

\(=14,13-4,13=10\)

b)\(60-26,75-13,25\)

\(=\)\(60-\left(26,75+13,25\right)\)

\(=60-40=20\)

c)\(38,25-18,75+21,64-11,64+9,23\)

\(=\left(38,25-18,75\right)+\left(21,64-11,64\right)+9,23\)

\(=9,5+10+9,3\)

\(=19,5+9,3=28,8\)

Phần này mk ko chắc đâu nhé.

d)\(\left(72,69+18,47\right)-\left(8,47+22,69\right)\)

\(=72,69+18,47-8,47-22,69\)

\(=\left(72,69-22,69\right)+\left(18,47-8,47\right)\)

\(=50+10=60\)

e)\(60-13,75-26,25\)

\(=60-26,25-13,75\)

\(=33,75-13,75=20\)

g)\(15,27-4,18-2,09\)

\(=15,27-2,09-4,18\)

\(=13,18-4,18=9\)

h)\(45,28+52,17-15,28-12,17\)

\(=\left(45,28-15,28\right)+\left(52,17-12,17\right)\)

\(=30+40=70\)

i)\(\left(8,27+7,16+9,33\right)-\left(7,27+6,16+8,33\right)\)

\(=8,27+7,16+9,33-7,27-6,16-8,33\)

\(=\left(8,27-7,27\right)+\left(7,16-6,16\right)+\left(9,33-8,33\right)\)

\(=1+1+1=3\)

Viết cái đống này mak hoa cả mắt. Mk đã tốn công vậy rùi nên bn nhất định phải k cho mk đó nha.(ko mk giận đó)

 b) 38,25 + 21,64 - 18,25 - 11,64 

= 38,25-18,25 + 21,64-11,64

=30

c) 4,86 x 0,25 x 40   

= 4,86 x (0,25 x 40)

=48,6

e) 0,125 x 6,94 x 80   

= (0,125 x 80) x 6,94

=69,4

a. 60 - (26,75 + 13,25) = 60 - 40 = 20

b. (38,25 - 18,25) + (21,64 - 11,64) = 20 + 10 = 30

c. 4,86 x (0,25 x 40) = 4,86 x 10 = 48,6

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a, 15,27 - 4,18 - 2,09

= 15,27 - (4,18 + 2,09)

= 15,27 - 6,27

= 9

b) 60 - 26,75 - 13,25

= 60 - (26,75 + 13,25)

= 60 - 40

=20

a: \(60-26,75-13,25\)

\(=60-\left(26,75+13,25\right)\)

\(=60-40=20\)

b: \(38,25-18,25+21,64-11,64+9,93\)

\(=\left(38,25-18,25\right)+\left(21,64-11,64\right)+9,93\)

\(=20+10+9,93=39,93\)

c: \(45,28+52,17-15,28-12,17\)

\(=\left(45,28-15,28\right)+\left(52,17-12,17\right)\)

=30+40

=70

d: \(\left(72,69+18,47\right)-\left(8,47+22,69\right)\)

\(=72,69+18,47-8,47-22,69\)

\(=\left(72,69-22,69\right)+\left(18,47-8,47\right)\)

=50+10

=60

nhanh lên giúp mik.mik đang cần gấp