Answer:
x = 25/3 y = -19/3
Step-by-step explanation:
First, solve for one of the variables:
-6 + 4x + y = 21 --> 4x + y = 27 --> y = -4x + 27
Then plug in y into the original equation to obtain x
x - 2(-4x + 27) = 21 --> x + 8x - 54 = 21 --> 9x = 75 --> x = 25/3
Then plug this x value in the original equation to obtain y
(25/3) - 2y = -6 + 4(25/3) + y --> 25/3 - 2y = -6 + 100/3 + y --> 25/3 - 2y = 82/3 + y --> -3y = 57/3 --> -3y = 19 --> y = -19/3
