1) 5x - y = 10
2) 3y - x = 5 or 3y - x = -5
3) 3y - x - 5x - y = -1

First we solve equation 1 for y:
y = 5x - 10

Now we substitute y in equation 2:
3(5x - 10) - x = 5
15x - 30 - x = 5
14x - 30 = 5
14x = 35
x = 35/14
x = 5/2

Now we substitute x back into equation 1:
5(5/2) - y = 10
25/2 - y = 10
y = 25/2 - 10
y = 5/2

So the solution to the system of equations is x = 5/2 and y = 5/2.