im a senior in high school and doing credit recovery and need help with math a lot.

## Solve using substitution: -y - 5x = -7 2y - 2x = 14

Tutors, please sign in to answer this question.

# 2 Answers

First, solve one of the equations for one of the expressions:

-y -5x = -7

+5x +5x

-y = 5x - 7

y = -5x + 7

Then, substitue this for y in the other equation:

2(-5x + 7) -2x = 14

-10x +14 - 2x = 14

-12x +14 = 14

-14 -14

-12x =
0

-12 -12

x = 0

Then, solve the other equation by substituting this value for x.

y = -5x + 7

y = -5(0) +7

y = 0 + 7

y = 7

Now check your work:

-y-5x=-7 Solve where x=0 and y=7

-7 -5(0) = -7

-7-0=-7

-7 = -7

2y-2x=14 Solve where x=0 and y=7

2(7) -2(0) = 14

14-0=14

14=14

Sean

Lets label the two equations as A) and B):

A) -y-5x=-7

B) 2y-2x=14

First, we can solve equation A) for y, as follows:

Add 5x to both sides:

**-y=-7+5X**Multiply both sides by -1:

**y=7-5x**Next we can

**substitute**this result for y into equation B), simplify, and solve for x as follows:B) 2(7-5x)-2x=14

14-10x-2x=14

14-12x=14

-12x=14-14

-12x=0

**x=0 We have now solved for x.**

Finally, we can plug 0 in for the value of x in

**either**equation, to solve for y. Let's use equation A):A) -y-5x=-7

-y-(5)(0)=-7

-y=-7

**y=7**

**We have now solved for y.**

We can check this result by substituting the values for x and y (0 and 7) back into each equation A) and B) to ensure that the values work. This can be left to the student.

Hope this helps!

George T.