Richard needs 18 cups of flour to make 78 pancakes. How many pancakes can Richard make with 12 cups of flour?

52.

Since he need 18 cups of flour to make 78 pancakes and now he only has 12 cups, take the gcd of 18 and 12, which is 6, now divide both 18 and 78 by such a number that 18/x = 6. So basically, x = 3. so with 6 cups he can make 26 pancakes, double that you get, with 12 cups he can make 52 pancakes.