An Internet store charges a base fee plus $1.50 per pound to ship items. The table shows samples of their shipping rates.
Shipping Rates
Weight of Package
(pounds)
Shipping Cost
(dollars)
2
8.00
5
12.50
7
9
18.50
10
17
30.50
Derek wants to ship items that weigh a total of 7 pounds, and Keisha wants to ship items that weigh a total of 10 pounds. How much more does Keisha pay for shipping than Derek?