Troy’s new puppy Rocco needed to run around outside, but Troy’s backyard did not have a fence. To keep Rocco from running away, Troy placed a metal rod in the middle of the yard and attached one end of a 20-foot leash to the pole with the other end attached to Rocco. After a few weeks, Troy noticed that Rocco had destroyed all the grass within his reach. Troy bought packets of seeds to plant, each packet covering an area of 40 square feet. The packets were usually priced at $4.50, but Troy found a sale of 4 for $15. He also found a coupon online for 7% off the total purchase price.

How much did Troy pay for the seed to replant the damaged lawn?