Answer:
x=-4 y=-7
Step-by-step explanation:
-4x+y=9 get y alone
add 4x both sides
y=4x+9
insert into y=2x+1
2x+1=4x+9
subtract 1 both sides
2x=4x+8
subtract 4x both sides
-2x=8
divide by -2
x=-4
y=2x+1
y=2(-4)+1
y=-8+1
y=-7
check
-4(-4)+(-7)=9
-16+(-7)=9
9=9
x=-4
y=-7
gl