solve x+3y=12 for x
Add -3y to both sides
x+3y+-3y= 12+-3y
x= -3y+12
Substitute -3y+12 for x in -4x+3y= -3
-4x+3y = -3
-4(-3y+12)= + 3y = -3
Simplify both sides of the equation
15y-48= -3
Add 48 to both sides
15y-48+48= -3+48
15y = 45
Divide both sides by 15
15y/15 = 45/15
y= 3
Substitute 3 for y in x = -3y+12
x = -3y+12
x= (-3)(3)+12
Simplify both sides of the equation
x= 3
Answer : x= 3 and y= 3
(3,3)
C is the answer
I hope that's help !