Ok I KNOW that spelling really doesn't matter b/c this is more like a conversation than an essay. BUT, were I to try to prove to someone how much smarter I am than they, I would spell "your" in its correct form, being "you're" when telling someone that "They're" 70 yrs old. Just so I didn't look stupid.
I have tried to help him out with that myself. It ends up that, only at the "junior college" that I must have attended, do they fret over such nonsense.
At the Ivy League colleges, such as the one Topper attended, they dismiss that sort of thing, and get right to what "really matters."