10x = 180 - 20
10x = 160
x = 16
x + 7 = 60 - 34
x + 7 = 26
x = 26 - 7
x = 19
4x = 240 - 40
4x = 200
x = 200 : 4
x = 50
3x = 450 - 150
3x = 300
x = 300 : 3
x = 100
1000x = 100000
x = 100000 : 1000
x = 100
50 : x = 50 - 48
50 : x = 2
x = 50 : 2
x = 25
15 - x = 216 : 18
15 - x = 12
x = 15 - 12
x = 3