Answer:
1. x = 11
Explanation:
1. x + 7 = 18
move 7 to right then change the sign
x = 18 - 7
x = 11
2. x - 13 = 15
move -13 to right then change the sign
x = 15 + 13
x = 28
3. 8x = 64
8 8
divided by 8 both side
x = 8
4. 5x-13-12=0 it this the correct given?
add same variable
5x = 13 + 12
5x = 25
5 5
divided by 5 both side
x = 5