Find the solution of this system of equations. separate the x- and y-values with a comma.
x= -6+y

x-3y=28

X = -6 + y...so we sub in -6 + y for x in the other equation

x - 3y = 28
-6 + y - 3y = 28
-2y - 6 = 28
-2y = 28 + 6
-2y = 34
y = -34/2
y = - 17

x = -6 + y
x = -6 - 17
x = - 23

solution is (-23,-17)