(36 + 54) × 7 + 7 × 9 + 7

= 90 × 7 + 7 × 9 + 7

= (90 + 9 + 1 ) × 7

= 100 × 7

= 700

A = 700

a.\(\dfrac{18}{15}+\dfrac{7}{15}+\dfrac{12}{15}=\dfrac{18+7+12}{15}=\dfrac{37}{15}\)

b.\(\dfrac{9}{7}+\dfrac{8}{7}+\dfrac{11}{7}=\dfrac{9+8+11}{7}=\dfrac{28}{7}=4\)

`=1,25xx(1+2+7)=1,25xx10=12,5`

a) = 1,25 x ( 2 + 7 + 1 )

= 1,25 x 10

= 12,5

12,5

\(a,=\left(\dfrac{3}{5}+\dfrac{3}{5}+\dfrac{6}{5}\right)\times\left(\dfrac{6}{7}:7\right)=3\times\dfrac{6}{49}=\dfrac{18}{49}\)

\(\dfrac{3}{5}\times\dfrac{6}{7}+\dfrac{3}{5}:7+\dfrac{6}{5}\\ =\dfrac{3}{5}\times\dfrac{6}{7}+\dfrac{3}{5}\times\dfrac{1}{7}+\dfrac{6}{5}\\ =\dfrac{3}{5}\times\left(\dfrac{6}{7}+\dfrac{1}{7}\right)+\dfrac{6}{5}\\ =\dfrac{3}{5}+\dfrac{6}{5}=\dfrac{9}{5}\)

giải giùm mình nhen mn. lu

\(a,\left(25\times32\right):8=25\times\left(32:8\right)=25\times4=100\\ b,\left(56\times125\right):7=\left(56:7\right)\times125=8\times125=1000\)

=100

=1000

8/5

686/65

5/7

3/5+7/12+5/12

=3/5+(7/12+5/12)

=3/5+1

=8/5

a.3/5+1=8/5

b.4/26+52/5=686/65

c.(9/16+7/16)*5/7=1*5/7=5/7

a) 4 x 78 x 5

= (4 x 5) x 78

= 20 x 78

= 1560

b) 2 x 99 x 5

= (2 x 5) x 99

= 10 x 99

= 990

\(7,\)

\(a,=\left(4\times5\right)\times78=20\times78=1560\)

\(b,=\left(2\times5\right)\times99=10\times99=990\)

a. 4 x 78 x 5 = 4 x 5 x 78 = 20 x 78 = 1560

b. 2 x 99 x 5 = 2 x 5 x 99 = 10 x 99 = 990

Giải đấy đủ giúp mình với 

a: =8/15x1/4=2/15

b: \(=\dfrac{5}{3}\cdot\dfrac{4}{5}\cdot\dfrac{6}{7}=\dfrac{24}{21}=\dfrac{8}{7}\)

c: \(=\dfrac{2}{5}\left(\dfrac{3}{7}+\dfrac{4}{7}\right)=\dfrac{2}{5}\)