Brenda and nine of her friends want to order a pizza. They decide that each person will eat 2 slices. If each pizza has 4 slices, how many pizzas should they order? Think carefully first, then make a decision:
All together, Brenda and her friends make a group of 1 + 9 = 10 people. If they each want to eat 2 pizza slices, there should be 10 * 2 = 20 slices. Since a pizza has 4 slices, they will have to order 20 / 4 = 5 pizzas. So, the answer is 5.