# How do you find the solution of the system of equations x+3y=12 and x-y=4?

May 13, 2015

x + 3y = 12 (1)

x - y = 4 (2)

(1) gives x = 12 - 3y. Replace x by (12 - 3y) into (2):

12 - 3y - y = 4 -> -4y = -8 -> y = 2

x = 12 - 3(2) = 6

Check:
(1): 6 + 6 = 12. Correct

(2) : 6 - 3 = 4. Correct