10x-25=25 21x-12=30 42-7x=0

Răspuns :

10x-25=25
10x=50
x=5

21x-12=30
21x=42
x=2

42-7x=0
-7x=-42
x=6


10x=50
x=50/10=5

21x=42
x=42/21=2

-7x=-42
7x=42
x=42/7=6