tolong bantu beserta caranya..besok dikumpulin

1. 4y -12 = 8
4y = 8+12
4y = 20
y = 20/4
y = 5

2. 6a+9 = -15
6a = -15-9
6a = -24
a = -24/6
a = -4

3. 3x+5= 2x-2
3x-2x = -2-5
x = -7

4. 9z -12 = 5+8z
9z -8z = 5+12
z = 17

semoga membantu