Steps:
1. Change x + y= 27 into y=mx+ b form
2. Subtract x on both sides
Y= -x + 27
3. Substitute the y in x + 3y= 73 for -x + 27
X + 3(-x + 27) = 73
X + -3x + 81= 73
-2x + 81= 73
4. Now subtract 81 on both sides
-2x=-8
5. X= 4
6. Now solve for y
7. Now substitute the x in x + y= 27 for 4
8. 4 + y= 27
9. Subtract 4 on both sides
10. Y= 23
11. Your answer is: x= -4 and y= 23 or (-4,23)
