Tolong kasih dan jawab dong ini kaya mana

2a) 2x + 7 = 15
2x = 15 - 7
2x = 8
x = 8 ÷ 2
x = 4
b) 3x - 4 = 16
3x = 16 + 4
3x = 20
x = 20/3
c) 4y + 5 = y + 14
4y - y = 14 - 5
3y = 9
y = 9 ÷ 3
y = 3
d) 5y - 6 = 3y - 12
5y - 3y = - 12 + 6
2y = - 6
y = - 6 ÷ 2
y = - 3

3a) y = x + 4
y = 0 => 0 = x + 4 => x = - 4
x = 0 => y = 0 + 4 => y = 4
b) y = 2x - 6
y = 0 => 0 = 2x - 6 => 2x = 6 => x = 3
x = 0 => y = 0 - 6 => y = - 6
c) x + 2y = 8
y = 0 => x + 0 = 8 => x = 8
x = 0 => 0 + 2y = 8 => y = 4
d) 3x + y = 6
y = 0 => 3x + 0 = 6 => 3x = 6 => x = 2
x = 0 => 0 + y = 6 => y = 6

buat no 4 gak jelas soalnya