Using elimination method you'll have:
x + 5y = 7 ----equation 1
-x + 2y = 0 ---equation 2
adding equations 1 and 2 you'll have
x + 5y = 7
+ -x + 2y = 0
7y = 7
y = 1
multiplying equation 1 by 2 and equation 2 by 5 you'll have:
(x + 5y = 7) x 2 => 2x + 10y = 14 ----equation 3
(-x + 2y = 0) x 5 => -5x + 10y = 0 ----equation 4
subtracting equation 4 from equation 3 you'll have:
2x + 10y = 14
- -5x + 10y = 0
7x + 0y = 14
7x = 14
x = 2
