The surface area of the recipe pan is... base (9x11) + 2 sides 2(9x2) + 2 more sides 2(11x2) which equals 179in²
the surface area of your pan is... base (10x10) + 2 sides 2(10x2) + 2 more sides 2(10x2) which equals 140in²
HOWEVER the answers above don't answer the question whether or not its ok to use your pan. You need to calculate volume:
Recipe pan: 9x11x2= 198in³
Your pan: 10x10x2= 200in³
In reality this would probably be fine, but for the sake of the math problem I would say no you can't use it because they aren't equal. However you know your teacher better than I do so thats up to you. Hope this helps :)
I'll edit my answer when you give more context, but for now, say you knew the values of A and B. Say A is 3 and B is 13. In order to find out C you'll need to subtract A from B; 13-3=10. C=10 in this situation.
Notice that for any increase, x * l or x * r, in length or radius, the increase in surface area is x squared (x2) and the increase in volume is x cubed (x3).
