Номер 85 помогите пожалуиста

1) x:20 = 2:5
x*5 = 20*2
5x=40
x=40:5
x=8

2) x:18 = 7:9
x*9 = 18*7
9x = 126
x = 126:9
x = 14

3) x:18 = 2:3
x*3 = 18*2
3x = 36
x = 36:3
x = 12

4) 6:x = 3:7
x*3 = 6*7
3x = 42
x = 42:3
x = 14

5) 5:9 = 15:x
5*x = 9*15
5x = 135
x = 135:5
x = 27

6) 12:7 = 60:x
12*x = 7*60
12x = 420
x = 420:12
x = 35