Question

Solve the following system of equations using substitution. What is the value of y?

2x+3y=105
x+2y=65
I somehow got -1(4/6)x=-5. Can someone provide a clear explanation on how to do this?

Answer 1

I have no idea how did you get this result but I can show you the method of elimination. I think that it is the easiest way to solve the system of equations.
2 x + 3 y =105
x + 2 y = 6 /*(-2) // We will multiply 2nd equation by -2. That is because we want to cancel out the x`s//
2 x + 3 y = 105
-2 x - 4 y = -12 // Then we will add down these equations/ and x`s will cancel out//
3 y - 4 y = 105 - 12
- y = 93
y = -93
We can also solve x:
x + 2 * (-93)=6
x - 186 = 6
x = 6 + 186
x = 192