Answer :
y=4x+6
y=-5x-21
4x+6=-5x-21
add both sides by 5x
also subtract both sides by 6
9x=-27
x=-3
plu x=-3 in y=6+4x
y=6-12
y=-6
y=-5x-21
4x+6=-5x-21
add both sides by 5x
also subtract both sides by 6
9x=-27
x=-3
plu x=-3 in y=6+4x
y=6-12
y=-6
y=6+4x
y=-5x-21
=> 6+4x=-5x-21
9x=-27
x=-3
y=6+4*(-3)=6-12=-6
y=-6
Solution: (-3; -6)
