On both equations, you have a similar term, but with opposite sign: 2y
Applying elimination means to add the two equations:
(5x + x) + (2y - 2y) = (17 + 8)
Making calculations, you get:
6x = 25
Therefore: x = 25/6
You can now substitute this value in either one of the original equations, after solving for y:
x - 2y = 8
-2y = 8 - x
2y = x - 8
y = (x - 8) / 2
y = ((25/6) - 8) / 2 = ( - 23/6) / 2 = -23/12
Therefore:
x = 25/6
y = -23/12