I am assuming that finding the x and y value is the goal for this question since it is not clarified.
So x = y + 3 is a equation we can plug in for x to find the y value.
-2(y+3) + 9y = 8
-2y - 6 + 9y = 8
7y - 6 = 8
7y = 15
y = 15/7
Plug in for the y value since that is now determined to find out x value.
x = 15/7 + 3
x = 15/7 + 21/7
x = 36/7
