I really really don't know (Khan Academy) I've tried many times Please help me i have to get to 15% and i'm only in 8%

Welcome to the forum Brainfreezezeve :)     

Is your name eve?

I like your username except I am wondering,  

What is the extra z for?      

Why do you have to be in 15% ?

Make sure you understand and can repeat my answer or else you are not learning anything ://

92+9y+18 and 36-y2

I suspect you meant 

y^2+9y+18 and 36-y^2

$y^2+9y+18=(y+3)(y+6)\\ ~\\ 36-y^2=6^2-y^2=(6-y)(6+y)=(6-y)(y+6)$

So the factor that they share is (y+6)