Me, i really need with these. dont answer if you dont know how. i really need

if a ii b what is the value of x?

answer for each .

1)
5x + 15 =115
5x = 100
x = 20
2)
4x+28=68
4x = 40
x = 10
3)
10x-40=50
10x = 90
x = 9
4)
10x-40+50=180
10x+10=180
10x = 170
x = 17
5)
6x-10 +3x+100 = 180
9x+90=180
9x = 90
x = 9

The solution to the system of equations (-2,2)