Question

Use elimination to solve the system 8x - 7y = 5 and 3x - 5y = 9 for y. A -2 B 8 C -1

Answer 1

The process of elimination is where you set the two equations up like a subtraction problem and cancel out one of the variables. We first need to manipulate the equations so that we can get one of the variables to be the same in both equations.

One way to do so would be multiplying the first equation by 3 and the second equation by 8. That gives us the following:

24x - 21y = 15
24x - 40y = 72

Now multiply one of them by -1 so that we can cancel the x out

 24x  - 21y =  15
-24x + 40y = -72
_______________
0x    + 19y = -57

y = -57/19
y=-3