5x + y = 6 (1)
5x + 3y = 8 (2)
Rearrange (1) to make 5x the subject of the equation
5x + y = 6
5x = 6 - y (3)
Substitute 5x in (3) for x in (2)
(5x) + 3y = 8
(6 - y) + 3y = 8
Simplify and then solve for y
(6 - y) + 3y = 8
3y - y + 6 =8
2y = 8 - 6
=
y = 1