Answer :
3x-y=0 is very simply seen to be y=3x, and then you can use this value of y in the other equation to get:
2x+y=-10 becomes:
2x+3x=-10
5x=-10
x=-2, making y=3x become:
y=3(-2)
y=-6, so the solution to the system of equations is the point (-2, -6)
2x+y=-10 becomes:
2x+3x=-10
5x=-10
x=-2, making y=3x become:
y=3(-2)
y=-6, so the solution to the system of equations is the point (-2, -6)