System of equations

X+3y=73

X+y=27

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)

X+3y=73

x+y=27

Multiply the second equation by - 3.

x+3y=73

-3x-3y=-81

Now add.

-2x=-8

x=4

Plug in 4.

4+y=27

Subtract 4 from both sides.

y=23