a,  \(\dfrac{5\times11\times15\times18}{6\times15\times22\times10}\)

= \(\dfrac{5\times11\times15\times6\times3}{6\times15\times11\times2\times2\times5}\)

= \(\dfrac{5\times11\times15\times6}{5\times11\times15\times6}\) \(\times\) \(\dfrac{3}{2\times2}\)

= 1 \(\times\) \(\dfrac{3}{4}\)

= \(\dfrac{3}{4}\)

b, \(\dfrac{7}{12}\) \(\times\) \(\dfrac{3}{5}\) + \(\dfrac{3}{5}\) \(\times\) \(\dfrac{5}{12}\)

= \(\dfrac{3}{5}\) \(\times\) ( \(\dfrac{7}{12}+\dfrac{5}{12}\))

= \(\dfrac{3}{5}\) \(\times\) \(\dfrac{12}{12}\)

= \(\dfrac{3}{5}\) \(\times\) 1 

= \(\dfrac{3}{5}\)

15 x 5 x 3 x ( 18 x 32 - 8 x 32 - 10 x 32 )

= 15 x 5 x 3 x { 18 - 8 - 10 } x 32 }

= 15 x 5 x 3 x 0

= 0 

Vì số nào nhân với 0 cx bằng 0 

15 x 5 x 3 x ( 32 x (18-8-10) 

15 x 5 x 3 x(32 x     0        )

15 x 5 x 3        0          = 0

             h nha

\(a,\dfrac{5}{13}\times\dfrac{4}{15}\times13=\dfrac{5\times4\times13}{13\times5\times3}=\dfrac{4}{3}\\ b,\left(\dfrac{3}{7}+\dfrac{5}{2}\right)\times\dfrac{7}{5}=\dfrac{3}{7}\times\dfrac{7}{5}+\dfrac{5}{2}\times\dfrac{7}{5}=\dfrac{3}{5}+\dfrac{7}{2}=\dfrac{6}{10}+\dfrac{35}{10}=\dfrac{41}{10}\\ c,\dfrac{1}{5}\times\dfrac{11}{18}+\dfrac{11}{18}\times\dfrac{3}{5}=\dfrac{11}{18}\times\left(\dfrac{1}{5}+\dfrac{3}{5}\right)=\dfrac{11}{18}\times\dfrac{4}{5}=\dfrac{22}{45}\)

a, 4/3  b, 41/10   c,22/45

=397x100=39700

= 397 x (20 + 82 - 2)

= 397 x (102 - 2)

= 397 x 100

= 39700

1: =354(4+5+1)-350

=3540-350

=3190

2: 

a: 19040:x=340

=>x=19040/340=56

b: x-3678=2541*4

=>x-3678=10164

=>x=10164+3678=13842

c: x*282-270*x=1512

=>12x=1512

=>x=126

d: =>(177-96+21):x=6

=>102:x=6

=>x=102/6=17

Có biết 436•75+43•24+436 thuận tiện ko mấy bạn

   42 x 3 + 18 x 32 + 18 x 61

= 6 x 7 x 3 + 18 x 32 + 18 x 61

= 18 x 7 + 18 x 32 + 18  x 61

= 18 x (7 + 32 + 61)

= 18 x 100

= 1800

\(42\times3+18\times32+18\times61\)

\(=6\times7\times3+18\times32+18\times61\)

\(=18\times7+18\times32+18\times61\)

\(=18\times\left(7+32+61\right)\)

\(=18\times100\)

\(=1800\)

=39700

\(397\times20+397\times82-397\times2\\ =397\times\left(20+82-2\right)\\ =397\times100=39700\)

 36-4x9 = 36 - 36 = 0 Vì số nào nhân với 0 thì cũng bằng 0 nên phép tính đó bằng 0