помагите все уравнения даю 30 балов

1. 50-11•х = 28
-11х = 28-50
-11х = 22
х = 2

2. х+50•100 = 700
50х+100 = 700
50х = 700-100
50х = 600
х = 12

3. 87-х:4 = 68
87-1/4х=68
348-х=272
-х = 272-348
-х = -76
х = 76

4. 36+х•2=50
36+2х=50
2х = 50-35
2х = 14
х = 7