Hello Elizabeth. It looks to me like this is a ratio problem. Has your teacher said anything about what the 'perfect' s'more should consist of? something like "twice as much cracker as there is chocolate, and equal amounts of chocolate and marshmallow"?
If you have a ratio you can put it into an equation fairly easily by defining variable x as the amount of graham crackers you need, and then the chocolate and marshmallows as fractions of that, and all of that equaling the amount of s'more. In the example I gave above, this would come out to be x (for the crackers) + x/2 (for the chocolate) + x/2 ('mallows) = 97.8 g
Without my inserts: x + x/2 + x/2 = 97.8 g
That's a pretty easy equation to solve--Just remember to include your units in the answer!