6x+15y=-45
6x+5y=-35
subtract second equation from the first
6x+15y=-45
6x+5y=-35
- - +
10y = -10
⇒ y = (-10/10) = 1
put value of y in one of the equation,
6x+5y = -35
⇒ 6x + 5(-1) = -35
⇒ 6x - 5 =-35
⇒ 6x = -35 + 5 = 30
⇒ x = 30/6
⇒ x = 5
So x=5 and y=-1.