a)  14 15

b)  5 5 = 1

mình hứa sẽ tick

= 2/5 + 1/5 + 1/5

= 4/5

b. = 2/7 + 4/7 + 5/21

= 6/21 + 12/21 + 5/21

= 23/21

HT

a)\(\dfrac{22}{25}+\dfrac{25}{125}+\dfrac{36}{96}\)
\(=\dfrac{22}{25}+\dfrac{1}{5}+\dfrac{3}{8}\)
\(=\dfrac{176}{200}+\dfrac{40}{200}+\dfrac{75}{200}\)
\(=\dfrac{291}{200}\)
b)\(\dfrac{22}{77}+\dfrac{56}{98}+\dfrac{25}{105}\)
\(=\dfrac{2}{7}+\dfrac{4}{7}+\dfrac{5}{21}\)
\(=\dfrac{6}{7}+\dfrac{5}{21}\)
\(=\dfrac{18}{21}+\dfrac{5}{21}=\dfrac{23}{21}\)

Ngu như con cặc

a, =1/4 + 5/6

=3/12 + 10/12

=13/12

\(\frac{2}{8}\)+\(\frac{5}{6}\)

=\(\frac{1}{4}\)+\(\frac{5}{6}\)

=\(\frac{6}{24}\)+\(\frac{20}{24}\)

=\(\frac{13}{12}\)

12/18_12/42

a) ( 25 915 + 142 ) : 71

= 26057 : 71

= 367.

b) 1029 - 884 : 34 x 21

= 1029 - 26 x 21

= 1029 - 546

= 483.

3 15   +   2 5   =   1 5   +   2 5   =   3 5

2 5   :   3 10   =   2 5   x   10 3   =   20 15   =   4 3

a: =2/3-1/3=1/3

b: =3/5-1/7=21/35-5/35=16/35

c: =2/3-1/2=4/6-3/6=1/6

tự làm , ngu

a)  2 5 + 3 6 = 12 30 + 15 30 = 27 30 = 9 10

b)  21 30 - 9 30 = 12 30 = 2 5

c)  5 8 × 4 7 = 20 56 = 5 14

d)  7 9 ÷ 11 6 = 7 9 × 6 11 = 42 99 = 14 33