I'm trying to do algebraic operations on the cells
so if I enter (all in a single cell):

2x+2y+y -----I would get---- 2x + 3y ----------in the same cell when I
press enter
x+y+z -----I would get ----- x+y+z -----------in the same cell when I
press enter
10+x+4x+y+y -----I would get----- 10+5x+2y---in the same cell when I press
enter

I hope that explain what I'm trying to do better, sorry I was vague before.