Imagine that you're standing at a vending machine. You want to buy a bottle of juice, which costs 75 cents, and a granola bar, which costs $1.10. You need to know how much money you'll need to buy both items. Would you know how to do it?
A lot of word problems tell about amounts that a person spends. For some problems, we add. For some problems, we subtract.
In these problems, if a person buys more of something or buys several different things, then we add the lesser amounts together to get a greater number (larger number).
If a person sells something or loses some money, we subtract one amount from the other amount. We end up with a lesser number (smaller number).
Let's look at the example in the first paragraph again. The juice costs 75 cents, and the granola bar costs $1.10. These are our two addends (numbers to be added together). Do we need to add them or subtract them? The problem says that you are trying to buy both items. That means that you need to add the two amounts together.
Remember that when you add dollar amounts, you use column addition.
$1.10
+ $ .75
$1.85
You have the sum (answer). The two items together will cost 1 dollar and 85 cents, or $1.85.
