Bill likes pepperoni pizza, and Howard like sausage pizza. Both are willing to eat pizza with sausage and pepperoni both. They order 10 pizzas total, each of which has either sausage or pepperoni and some of which have both. If 6 have pepperoni on them, and 8 have sausage on them, how many pizzas have both sausage and pepperoni on them?
Impossible to tell
Explain your answer.