Well, he will obviously be using 12 cups of pretzels, so let's set that aside. For every cup of pretzels, there are 3 cups of chex. So, multiply 3x12. That will give you how much chex you will need.
The total of the prices of all of the baby shirts and sweaters that the store sold during the sale was $420.00. It's possible that 12 sweaters and 8 shirts are sold a bargen