Answer:
y = 4
x= 7
Step-by-step explanation:
First you would rearrange the first equation x-7y=-21 and make x the subject:
x= -21 +7y
Then substitute x into the 2nd equation to find y:
13x - 7y= 63
13(-21+7y) - 7y = 63
-273 + 91y -7y = 63
-273 + 84y=63
84y = 63 + 273
84y = 336
y = 4
Once you have y you can substitute this into any of the original equations to find x, for example:
x - 7y = -21
x - 7(4) = -21
x - 28 = -21
x = -21 +28
x= 7
