Question

1. Solve the system of equations by substitution and check your solution.
x = 1 - 3y
3x + 3y = 15

Answer 1

Answer:

x = 7 and y = −2

(7, -2)

Step-by-step explanation:

x = 1 - 3y

3x + 3y = 15

Substitute −3y + 1 for x in 3x + 3y = 15:

3(1 - 3y) + 3y = 15

3 - 9y + 3y = 15

3 - 6y = 15

-3           -3

-6y = 12

/-6     /-6

y = -2

Now we solve for x. Substitute −2 for y in x = −3y + 1:

x = 1 - 3y

x = 1 + (-3)(-2)

x = 1 + 6

x = 7

Now we check our solution.

x = 1 - 3y

7 = 1 + (-3)(-2)

7 = 7 ✅

3x + 3y = 15

3(7) + 3(-2) = 15

21 - 6 = 15

15 = 15 ✅