Karla went shopping and bought a dress for 5 1/2 dollars and a skirt for 2 3/5 dollars / If she paid for the clothes with a $20. how much money did she have left? how do I solve the problem using an equation or model

First, you want to find how much she spent. If you add up 5.5 and 2.6, you get $8.10

Now, you want to subtract $8.10 from $20 to see how much she has left. 20-8.1 is $11.90.

An equation you can use is 20 - (5 1/2 + 2 3/5) = How much money she has left