Question

How to work -1x-2y=-13 x-2y=11 equation by substitution

Answer 1

Well if you're wanting to use substitution, you first have to end up with one term on either side of the equation. Use the second one as it's easiest. 

So: x-2y=11, so find -2y as there is a -2y in the first equation. 
then that becomes -2y=11-x. then sub that into equation 1, and you get:

-x+11-x=-13, which equals to -2x+11=-13, which is -2x=-24, so therefore

x=12. then chuck the x into any of the equations to find what y equals. 

hope this helps!