Ana and Katrina are buying fruit to bring to their book club meeting. Ana buys 2.4 lb of oranges and 0.8 lb of cherries. Katrina buys 1.8 lb of oranges and 1.3 lb of cherries. Oranges cost r dollars per pound, and cherries cost c dollars per pound. Write and expression with exactly two terms for the total cost of the fruit Ana and Katrina buy. Show your work.