x+20=45,x-20=45,45-x=20

x+20 = 45

x= 45-20

x= 25

x-20 = 45

x= 45+20

x=65

45-x=20

x=45-20

x=25

x + 20 = 45
x = 45 - 20
x = 25
__________
25 + 20 = 45
45 = 45


х - 20 = 45
х = 45 + 20
х = 65
__________
65 - 20 = 45
45 = 45


45 - х = 20
х = 45 - 20
х = 25
___________
45 - 25 = 20
25 = 25