System of equations issue

[gcooper]

So, I have the following system:

4x + 5y = 16
3x - 10y = -37

Here's how I tried to solve it:

2(4x + 5y = 16)
8x + 10y = 32

add that to the lower equation and you get:

11x = -5
x = -5/11

But that is not the answer, x should be -1.

So where did I go wrong?

 

[Ishuda]

So, I have the following system:

4x + 5y = 16
3x - 10y = -37

Here's how I tried to solve it:

2(4x + 5y = 16)
8x + 10y = 32

add that to the lower equation and you get:

11x = -5
x = -5/11

But that is not the answer, x should be -1.

So where did I go wrong?

CHECK: x = -1
4x + 5y = 16 ==> -4 + 5y = 16 ==> 5y = 20 ==> y=4
3x - 10y = -37 ==> -3 - 10y = -27 ==> -10y = -30 ==> y=3
I don't think x=-1 is a proper solution (unless I've made a dumb misteak)

 

[gcooper]

checked it again, the equations are the right ones, and the answer at the end actually is -1. I guess its just a mistake made by the author.