The expression 11.02k+21 indicates how much did Gabe spend in the first store he visited.
In the second store, he spent 30 dollars.
To determine how much he spent in the mall you have to add the amounts he spent in both stores:
The expression that represents his total expenses at the mall is
"k" represents the number of items he bought. If he bought k=2 items, you can calculate how much he spent at the mall as follows:
Gabe spent an estimate of 72.04 dollars at the mall