Rodney is making three pizzas. The recipe says that, for one pizza, he needs 2 cups of flour, 2 teaspoons of instant active dry yeast, 2 cloves of garlic, 1 tablespoon of olive oil, and some other ingredients. Rodney is out of flour and goes to the store to buy a bag containing 20 cups of flour. How much flour will he have left over after making the pizzas?