Question

RESOLVA AS CONTAS
21=3x
84=6x
-7x=14
-5x=x-12
5x+7=4+10
(4x+6)-2x=(x-6)+10+14
7(x-5)=3(x+1)

Answer 1

21= 3x
-3x= -21
x= $\frac{-21}{-3}$ = +7

84= 6x
-6x= -84
x= $\frac{-84}{-6}$ = +14