solve system by subtraction.?

Question

5x-2y=-5
Y-5x=3
how do you do this problem?
or
8x-4y=16
y=2x-4
Im stumped

Answer 1

Put the terms in the same order, e.g.

4x - 7y = 10
2y + x = 15 => x + 2y = 15

Multiply the second equation by an amount so that you can eliminate a term, e.g.

4x - 7y = 10
x + 2y = 15 <= want to eliminate x, so multiply both sides of eq by 4

4x - 7y = 10
4x + 8y = 60

Subtract:

-15y = -50
y = 50/15 = 10/3

Then solve for the other term.