30-×=20. х+1=40. у-8=7

Question

30-×=20. х+1=40. у-8=7

Answer 1

1) 30-x=20
-x=20-30
-x= -10
x=10
2) x+1=40
x=40-1
x=39
3)y-8=7
y=7+8
y=15

Answer 2

30-x=20|x+1=40| y-8=7
x=30-20|x=40-1| y=8+7
x=10| x=39| y=15
30-10=20| 39+1=40| 15-8=7