Question

Solve using elimination. –x − 7y = –20 –6x − 7y = –15

Answer 1

x = −1 and y = 3

Multiply the second equation by -1, then add the equations together.

(−x−7y=−20)

−1(−6x−7y=−15)

Becomes:

−x−7y=−20

6x+7y=15

Add these equations to eliminate y:

5x=−5

Then solve5x=−5for x:

5x=−5

5x/5 = -5/5

x = -1

Now that we've found x let's plug it back in to solve for y.

Write down an original equation:

−x−7y=−20

Substitute−1 for x in −x −7y = −20:

−(−1)−7y=−20

−7y+1=−20(Simplify both sides of the equation)

−7y+1+−1=−20+−1(Add -1 to both sides)

7y = -21

-7y/-7 = -21/-7

y=3