Respuesta :

x=4
sub
-3(4)+9y=-57
-12+9y=-57
add 12 both sides
9y=-45
divide 9
y=-5
(4,-5)
y=5

-3x+9y=-57 for x=4

-3(4)+9y=-57

Simplify both sides of the equation

(-3)(4)+9y=-57

-12+9y=-57

9y-12=-57

Add 12 to both sides

9y-12+12=-57+12

9y=-45

Divide both sides by 9

9y/9=-45/9

y=-5


I hope that's help !