Solve the following system of equations using the substitution method.
–y = 5x + 21

–4x + y = 6
Question 1 options:

A)

(3,6)

B)

(3,–6)

C)

(–3,6)

D)

(–3,–6)

D

Step-by-step explanation:

Since we already know what -y is we can use that to find y.

y = -5x -21.

Let's substitute that in the bottom equation

-4x -5x - 21 = 6.

Simplify.

-9x = 27.

x = -3

Let's solve using

y = -5x -21.

to find y.

y = -5(-3) - 21

y = 15 - 21

y = -6.

There you have it!

x = -3, y = -6

So.. The correct answer choice is D