Hi, i'm new the forums so pardon me if i posted this question in the wrong section. I'm having trouble with these problem. I think i've got the answer but whenever i substitue a value in for X in the simplified equation, i get a different answer than the value i got if i did so with the orginal equations. What i'm saying may not be making any sense to you right now so please check the picture of the question and attached.

THANKS.