Question

Solve the following:

y = x + 3
4x + y = 18


(6, 3)

(3, 6)

(−3, 6)

(3, −6)

Answer 1

B (3 ; 6)

Explanation:

y = x + 3

4x + y = 18

4x + (x + 3) = 18

5x = 18 - 3

5x = 15

x = 3

y = x + 3

y = 3 + 3

y = 6

Answer 2

(3,6)

Explanation:

We can substitute y for x+3 in the second equation

4x + x + 3 = 18

5x = 15

x=3

Plug x back into the equation

y = 3 + 3

y = 6