What is the solution of equations?

Y= -3x-2
5x+2y=15

Since y=-3x -2 we shall replace this value of y in the second equation to get ..
5x+2(-3x-2)
=5x-6x-4
=-x-4,take the -4 to the other side and so we shall have
-x=4 ,divide both sides by -1 to get x=-4
So we shall go back to our first equation and replace x with the value we have so we shall get...
Y=-3(-4) -2
Y= 10