Question 529767
Notice 10 = 5*2.

5x + y = 9
10x - 7y = -18


If we multiply the top by -2, then we can add and eliminate x.

-2(5x+y) = -2*9

-10x - 2y = -18
10x - 7y = -18

-9y = -36

y = 4

5x + 4 = 9
5x = 5
x = 1

So our solution is (1,4)