Question

 giúp mình với ạ

Answer 1

Câu 3: 

a: =>12/7:x=7/5-2/3=21/15-10/15=11/15

=>x=180/77

b; =>3(x+2)=21

=>x+2=7

hay x=5

c: =>x=121/325

Answer 2

C1:

\(\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}=\dfrac{6}{12}+\dfrac{4}{12}+\dfrac{3}{12}=\dfrac{13}{12}\)