We are now working on systems of linear equations.  This is when you are given two equations and practically have to combine the two and use algebra to get X= or Y=.  Such as an equation of 2x+3y=7/5x-3y+28, first of all the +3y and -3y cancel each other out and are called a zero pair.  now we add what we have left which gives us 7x/7 and 35/7, we divide these both by 7 giving us x=5.