posted by Rose .
solve the system by the method of substitution
I got (0,2)
Try plugging in x=0 and y=2 into your first equiation and uopu will that your answer must be wrong.
Do it this way:
x - 4y =-21
12x+ 4y =8
13 x = -13
x = -1
y = 2 - 3x = ?
x=0 and y=2 does not satisfy the first equation.
(0)-4(2)=0-8=-8 but that isn't equal to -21.