4. A recipe for pancakes calls for 3/4 cup of flour and Bob is making it two and a half times the number of pancakes called for in the recipe. How much flour will he need?

This is an A = RB type of problem. The rate is 3/4 cup per recipe. Since the units of the rate are cups per recipe, the base is the number of recipes, so you multiply

Since we are multiplying, change the mixed number to an improper fraction.

Since the answer comes out as an improper fraction, you may want to change it to a mixed number. Divide the bottom into the top

and the answer is