Addition ans Substiution

Question

4x+13y=40

4x+3y=-40

What is the value of y?

Answer 1

4x + 13y = 40
4x + 3y = -40

 

Let's start off by multiplying the second equation by -1. Then we can use the elimination method:

4x + 13y = 40
-4x - 3y = 40

-------------------

10y = 80

 

Divide by 10:

y = 8