Answer :
assuming x=x and y=y in both equations
add them together
-4x+y=6
-5x-y=21 +
-9x+0y=27
-9x=27
divide by 9
-x=3
multiply -1
x=-3
subsiutte
-4x+y=6
-4(-3)+y=6
12+y=6
subtract 12
y=-6
x=-3
y=-6
the soultion set is in (x,y) form
(-3,-6)
add them together
-4x+y=6
-5x-y=21 +
-9x+0y=27
-9x=27
divide by 9
-x=3
multiply -1
x=-3
subsiutte
-4x+y=6
-4(-3)+y=6
12+y=6
subtract 12
y=-6
x=-3
y=-6
the soultion set is in (x,y) form
(-3,-6)