Question

помагите плиз очень нужна

Answer 1

2)
15 + 7x - 12 = 3x + 39
3 + 7x = 3x + 39
7x - 3x = 39-3
4x = 36
x = 36 : 4
x = 9

4)

7y - 1 - 3y - 3 = 8y + 20
4y - 4 = 8y + 20
4y - 8y = 20 + 4
-4y = 24 
y = -24 : 4
y = -6