Let's solve the system:
6+4x-2y = 0
-3-7y = 10x
Divide first equation by 2:
2x-y=-3
We solve for y:
y = 2x+3
In order to find x we replace y in the second equation:
-3-7(2x+3) = 10x
-3-14x-21=10x
-24 = 24x
x=-1
Bonus: To find y we simply compute 2x+3 but we replace x with -1
y = 2(-1)+3 = 1