I need help with solving equations with substitution I'm stuck on problem. like

x=-4y

3x+2y=20

and

y= -x+6

3x+y=-10

Can you guys also help me double check these?

4x+y=1

y=x-9

For this I got (2,7)

5x+y=4

y=2x-3

I got (1,-1) for this

Thanks for your help!