Alyssa's extended family is staying at the lake house this weekend for a family reunion. She is in charge of making pancakes for the entire group. The pancake requires 2 cups of flour for every 10 pancakes. If Alyssa has to make 70 pancakes, how many cups of flour will she have to use?  

Oops, not enough people showed up, and now she only needs to make 45 pancakes. How much flour?