Question

Fairly easy question

What is the solution to this system of equations?
x − 2y = 15
2x + 4y = -18
A.
x = 1, y = -6
B.
x = 1, y = -7
C.
x = 3, y = -6
D.
x = 3, y = -7

Answer 1

C. x=3 and y=−6

Explanation:

Step: Solvex−2y=15for x:

x−2y=15

x−2y+2y=15+2y(Add 2y to both sides)

x=2y+15

Step: Substitute2y+15forxin2x+4y=−18:

2x+4y=−18

2(2y+15)+4y=−18

8y+30=−18(Simplify both sides of the equation)

8y+30+−30=−18+−30(Add -30 to both sides)

8y=−48

8y8=−488(Divide both sides by 8)

y=−6

Step: Substitute−6foryinx=2y+15:

x=2y+15

x=(2)(−6)+15

x=3(Simplify both sides of the equation)

Answer:

x=3 and y=−6