Solve Systems of Equations Using Substitution

Question

Y=6

Y=5x+7

Answer 1

You know that y=6 so plug that into the second equation. What you have so far is 6=5x+7. Subtract 7 from both sides to get -1=5x. Divide 5 from both sides and you get -1/5=x. You know this is correct because if you plug -1/5 back into the second equation, it equals 6. 

Answer 2

Hi Conny;

Y=6
Y=5x+7

In the second equation, let's substitute y with 6...

6=5x+7

Let's subtract 7 from both sides...

-7+6=5x+7-7

-1=5x

Let's divide both sides by 5...

-1/5=(5x)/5

-1/5=x

Let's check our work...

Y=5x+7

6=[(5)(-1/5)]+7

6=-1+7

6=6