9514 1404 393
Answer:
(x, y) = (-3, -6)
Explanation:
The coefficients of y are opposites, so adding the two equations will cancel the y-terms.
(-4x +y) +(-5x -y) = (6) +(21)
-9x = 27 . . . . . simplify
x = -3 . . . . . . divide by -9
Now, we can find y.
-4(-3) +y = 6 . . . . . substitute for x in the first equation
y = 6 -12 = -6 . . . . subtract 12
The solution is (x, y) = (-3, -6).