Question

Find the solution to the following system by substitution.

x+y=18
y = 3x + 6
A. (6,24)
B. (15,3)
C. (4,18)
D. (3, 15)

Answer 1

D. (3, 15)

Explanation:

`x + y = 18`

`x + (3x + 6) = 18`

`x + 3x + 6 = 18`

`4x = 18 - 6`

`4x = 12`

`(4x)/(4) = (12)/(4)`

`x = 3`

Solve for y:

`y = 3x + 6`

`y = 3(3) + 6`

`y = 9 + 6`

`y = 15`