Can someone help me come up with a way to explain why this is linear? thanks

Georgia needs to buy flea treatment for her dog. pet store 1 is offering the flea treatment for 40 percent off plus an additional 25 percent off their regular price of $33. pet store 2 is offering the same flea treatment for 55 percent off plus an additional 5 percent off their regular price of $34. which location is offering the better price and how much cheaper is it? the flea treatment is $0.31 cheaper at pet store 2. the flea treatment is $1.05 cheaper at pet store 2. the flea treatment is $2.05 cheaper at pet store 1. the flea treatment is $2.36 cheaper at pet store 1.