Найдите неизвестный член пропорции: 8/14 = x/35; 7/28 = x/12; 4/x = 6/18; 14/10 = 21/x;

1:
8/14=x/35
14x=8*35
14x=280
x=280/14
x=20
2:
7/28=x/12
28x=7*12
28x=84
x=84/28
x=3
3:
4/x=6/18
6x=4*18
6x=72
x=72/6
x=12
4:
14/10=21/x
14x=10*21
14x=210
x=210/14
x=15