16,88 + 9,76 + 3,12

= (16,88 + 3,12) + 9,76

= 20 + 9,76

= 29,76

`3,12:0,25+3,12:0,2+3,12:0,5+3,12xx89`

`=3,12xx4+3,12xx5+3,12xx2+3,12xx89`

`=3,12xx(4+5+2+89)`

`=3,12xx100 = 312`

\(3,12:\dfrac{1}{4}+3,12:\dfrac{1}{5}+3,12:\dfrac{1}{2}+3,12\times89\)

\(=3,12\times4+3,12\times5+3,12\times2+3,12\times89\)

\(=3,12\times\left(4+5+2+89\right)\)

\(=3,12\times100=312\)

7,5 x 2,5 x 0,04

= 7,5 x ( 2,5 x 0,04 )

= 7,5 x 0,1

= 0,75

3,12 x 8 x 1,25

= 3,12 x ( 8 x 1,25 )

= 3,12 x 10

= 31,2

câu cuối tớ 0 bt cách làm ==

2 x 3,12 x 1,25 : 0,25 x 10

= 6,24    x 1,25 x 4     x 10

= 6,24   x        5          x 10

=         6,24  x       50

=             312

12,48 : 0,5 x 6,25 x 4 x 2

= 12,48 x 2 + ( 6,25 x 4 ) x 2

= 12,48 x ( 2 x 2 ) x 25

= 12,48 x ( 4 x 25 )

= 12,48 x 100

= 1248

2 x 3,12 x 1,25 : 0,25 x 10

= 2 x 3,12 x 1,25 x 4 x 10

= 2 x 3,12 x 5 x 10

= ( 2 x 5 ) x 10 x 3,12

= 100 x 3,12

= 312

3.12:0.25+12.48*3-3.12*6

=3.12*4+3.12*12-3.12*6

=3.12*(4+12-6)

=3.12*10

=31.2

= 3,12 x 4 + 3,12 x 4 x 3 - 3,12 x 6

= 3,12 x 4 +3,12 x 12 - 3,12 x 6

= 3,12 x ( 4 + 12 - 6 )

= 3,12 x 10

= 31,2

    3,12 : 0,25 + 12,48 x 3 - 3,12 x 6

=  3,12 x 4 + 3,12 x ( 4 x 3 ) - 3,12 x 6

= 3,12  x 4 + 3,12 x 12 - 3,12 x 6

= 3,12 x ( 4 + 12 - 6 )

= 3,12 x         10

= 31,2

3,12 : 0,25 + 12,48 x 3 - 3,12 x 6

=3,12 : 1/4 + 3,12 x 4 x 3 - 3,12 x 6

=3,12 x 4 + 3,12 x 12 - 3,12 x 6

=3,12 x (4 + 12 - 6)

=3,12 x 10

=31,2

   3,12 : 0,25 +12,48 x 3 - 3,12 x 6

= 3,12 x 4 + 3,12 x 12 - 3,12 x 6

=3,12 x (4 + 12- 6)

=3,12 x 10

= 31,2

a) 19,17x25x4=19,17(25x4)=19,17x100=1917

b)1,79x(8x125)=1,79x1000=1790

chúc bạn học tốt

B1:

a) = (8/15 + 7/15) + (7/4 + 5/4)

    = 15/15 + 12/4

    = 1 + 3

    = 4

b) = (16,88 + 3/12) + 9,76

     = 20 + 9,76

     = 29,76

c) = (17,16 + 82,84) + 72,84

    = 100 + 72,84

    = 172,84

B2:

2/3 + 4/5 = 10/15 + 12/15 = 22/15

a) \(\frac{8}{15}+\frac{7}{4}+\frac{7}{15}+\frac{5}{4}\)

\(=\left(\frac{8}{15}+\frac{7}{15}\right)+\left(\frac{7}{4}+\frac{5}{4}\right)\)

\(=\frac{15}{15}+\frac{12}{4}\)

\(=1+3=4\)

b) \(16,88+9,76+3,12\)

\(=\left(16,88+3,12\right)+9,76\)

\(=20+9,76=29,76\)

c) \(72,84+17,16+82,84\)

\(=\left(82,84+17,16\right)+72,84\)

\(=100+72,84=172,84\)

\(\frac{2}{3}+\frac{4}{5}=\frac{10}{15}+\frac{12}{15}=\frac{22}{15}\)

    8/15+7/4+7/15+5/4

=( 8/15 +7/15)+ (7/4+5/4)

=        1           +     3

=                    4

    16,88 + 9,76 +3,12

=(16,88+3,12)+9,76

= 20               +9,76

=       29,76

    72,84+17,16+82,84

=(72,84+17,16)+82,84

= 90                 +82,84

=172,84