### They must be the same, but can be different

Balancing chemical equations is like managing store inventory. For chemistry, it must always be true that the number of all elements must be the same before and after a reaction. For a store manager, he or she must make sure that the inventory at the beginning of the day must match all sold and remaining inventory at the end of the day.

### Creative Applications

A store manager opens up the week restocking store shelves. At the beginning of the week, he gets an inventory of 20 boxes of strawberries and 10 boxes of mangos. He uses two boxes of strawberries to make cakes for the bakery, sells 16 boxes, and has 2 boxes of strawberries leftover at the end of the week. He uses 3 boxes of mangos to bake cakes, and sells the rest to customers.

1. How many total boxes of strawberries and mangos should there be before and after the week, regardless if they were sold or not?

2. Using chemical equation format, show the original inventory of strawberries and mangos on the left, and what happened to them at the end of the week on the right?

3. Is it possible to have boxes of strawberries or mangos “disappear”? In other words, can the total number of boxes (bought, used, or unsold) be different than at the beginning of the week? (eating them doesn’t count)

4. How does this relate to balancing chemical equations?