156 x 7 – 56 x 7

= (156 – 56) x 7

=100 x 7 = 700  

(36 + 54) x 7 + 7 x 9 + 7

= 90 x 7 + 7 x 9 + 7

= (90 + 9 + 1 ) x 7

= 100 x 7

= 700

(36 + 54) x 7 + 7 x 9 + 7

= 90 x 7 + 7 x 9 + 7

= (90 + 9 + 1 ) x 7

= 100 x 7

= 700

=7/10(3+5+2)

=7/10*10

=7

3 x 7/10 + 7/10 x 5 + 2 x 7/10

= 7/10 x (3 + 5 + 2)

= 7/10 x 10

= 7

\(3\times\dfrac{7}{10}+\dfrac{7}{10}\times5+2\times\dfrac{7}{10}\)

\(=\dfrac{7}{10}\times\left(3+5+2\right)\)

\(=\dfrac{7}{10}\times10\)

\(=7\)

\(\dfrac{7}{10}\times\left(3+5+2\right)=\dfrac{7}{10}\times10=\dfrac{70}{10}=7\)

`3xx7/10+7/10xx5+2xx7/10`

`=7/10xx(3+5+2)`

`=7/10xx10`

`=7`

lx

Uả cái j zị

ảnh đâu 

42 x 2 x 7 x5

= (42 x 7) x (2 x5)

= 294 x 10 = 2940

= 3/2 x (4/7 + 3/7)

= 3/2 x   1

= 3/2

3/2 x ( 4/7 + 3/7 )

= 3/2 x 1

= 3/2

\(\dfrac{3}{2}\times\dfrac{4}{7}+\dfrac{3}{7}\times\dfrac{3}{2}\\ =\dfrac{3}{7}\times\dfrac{4}{2}+\dfrac{3}{7}\times\dfrac{3}{2}\\ =\dfrac{3}{7}\times\left(\dfrac{4}{2}+\dfrac{3}{2}\right)\\ =\dfrac{3}{7}\times\dfrac{7}{2}\\ =\dfrac{3}{2}\)