\(\dfrac{3\times145+3\times55}{6\times215+6\times85}=\dfrac{3\times\left(145+55\right)}{6\times\left(215+85\right)}=\dfrac{3\times200}{6\times300}=\dfrac{3\times100\times2}{3\times2\times100\times3}=\dfrac{1}{3}\)

18*(5773+2457)+5310*6

=18 *8230+53108*6

=18*(8230+53108)*6

=18*61238*6

=11102184*6

=6613104

k cho mình nha

NGU THẾ HẢ LINH

a) = \(\frac{5\cdot7\cdot8\cdot9\cdot10}{7\cdot8\cdot9\cdot10\cdot11}\)

    = \(\frac{5}{11}\) gạch hết các chữ số 7 , 8 , 9 , 10.

b) = \(\frac{3\cdot145+3\cdot55}{6\cdot215+6\cdot85}\)

   = \(\frac{3\cdot\left(145+55\right)}{6\cdot\left(215+85\right)}\)

   = \(\frac{3\cdot200}{6\cdot300}\)

   = \(\frac{1}{3}\)

Mình hỏi bạn Nguyễn Gia Huy dấu chấm là gì

dấu . là x nhé 

dấu nhân.

=870+165/1290+390

=1035/1680

=\(\frac{69}{112}\)

hình như bạn chép sai đề phải ko

nhớ kết bạn nha

a:

\(\frac{7x8x9x10}{9x8x7x12}\)

= \(\frac{7x8x9x2x5}{9x8x7x2x6}\)

= \(\frac{5}{6}\)

b: \(\frac{3x145+3x55}{6x215+6x85}\)

= \(\frac{3x\left(145+55\right)}{6x\left(215+85\right)}\)

= \(\frac{3x200}{6x300}\)

= \(\frac{3x100x2}{2x3x3x100}\)

= \(\frac{1}{3}\)

a)   \(\frac{7\times8\times9\times10}{9\times8\times7\times12}\)

\(=\frac{10}{12}=\frac{5}{6}\)

b)  \(\frac{3\times145+3\times55}{6\times215+6\times85}\)

\(=\frac{3\left(145+55\right)}{6\left(215+85\right)}\)

\(=\frac{3\times200}{6\times300}\)

\(=\frac{1}{3}\)

Đáp án :5/6

a) 145 + 86 + 14 + 55 = ( 145 + 55 ) + (86 + 14 )

= 200 + 100

= 300

b) 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = ( 1+9 +2 + 8) + ( 3 + 7 + 4 + 6 ) + 5

= 20 + 20 + 5

= 45

5/2+13/6+25/12+41/20+61/30+85/42

=2+1/2+2+1/6+2+1/12+2+1/20+2+1/30+2+1/42
=12+(1/2+1/6+1/12+1/20+1/30+1/42)

=12+(1/1.2+1/2.3+1/3.4+1/4.5+1/5.6+1/6.7)

=12+(1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7)

=12+1-1/7

=90/7

5/2+13/6+25/12+41/20+61/30+85/42

=2+1/2+2+1/6+2+1/12+2+1/20+2+1/30+2+1/42
=12+(1/2+1/6+1/12+1/20+1/30+1/42)

=12+(1/1.2+1/2.3+1/3.4+1/4.5+1/5.6+1/6.7)

=12+(1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7)

=12+1-1/7

=90/7

1)69.24+69.120+144.31

= 69. (24+120) + 144.31

= 144.69 + 144.31

= 144. (69+31)

= 144.100

=14 400

2)95.103-95.2-95

= 95. (103-2-1)

= 95.100

= 9 500

4)47.62+31.106

= 47. 62+ (31.2). 53

= 47.62 + 62. 53

= 62. (47+53)

= 62.100

= 6 200

5) 54.12+27.77-27

= 27. (2.12) + 27.77 - 27.1

= 27. 24 + 27.77 - 27.1

= 27. (24+77-1)

= 27. 100

= 2 700

6) 49+215+51+83+85

= (49+51) + (215+85)+ 83

= 100 +300 + 83

= 483