Elimination:
3x-4y=16
5x+6y=14

Okay for this one, i will start with x

3x - 4y = 16
5x + 6y = 14

I will multiply the top row with (-5) and the bottom with (3) 
so the new equation is

-15x + 20y = -80
15x + 18y = 42

After canceling (x) the new equation will be

38y = -38

Divide by 38

And you will get -1

Now substitute (-1) to (y)  to the old equation ( any of the old equation)
3x- 4(-1)= 16
x = 4

answers ( 4, -1)

Did you put in a negative answer? no matter if you + - ÷ or ×, it will be negative example: -21 ÷ 3 = -7