Explain simply why 4 is the correct answer to: Cupcakes are sold in packages of 10 and 15. Jean bought 4 packs of 15 cupcakes. If she will give one cupcake each to 100 children in the orphanage, how many packs of 10 cupcakes should she need to buy?. Explanation:
Jean already bought 15 cupcakes x 4 packs = 60 cupcakes. She needs 100 - 60 = 40 more cupcakes. Thus, she needs to buy 40 / 10 = 4 packs of 10 cupcakes.