Question

solve the system by the method of substitution

x-4y=-21
3x+y=2

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.