x+27=57, x-29=11, 37-x=7 как решить правельно

x + 27 = 57
x = 57 - 27
x = 30

x - 29 = 11
x = 11 + 29
x = 40

37 - x = 7
- x = 7-37
- x = - 30
x = 30

х+27=57
х=57-27
х=30

х-29=11
х=11+29
х=40

37-х=7
х=37-7
х=30