Hanna buys 3 packs of 36 exposure film and 2 packs of 24 exposure film. she uses 8 rolls of film. how many rolls does she have left?

To solve this problem, first we have to figure out how many total rolls Hanna buys.

3 packs*36 rolls in each pack = 108 total rolls
2 packs*24 rolls in each pack = 48 total rolls

108 rolls + 48 rolls = 156 rolls.

Next, it says that Hanna uses 8 rolls of film.  To model this in our expression, we need to subtract 8 rolls from our total amount.  

156-8 = 146 rolls

Hanna has 146 rolls left.

The question can't be answered with the given information . . . we don't know how many rolls there are in a pack.