What is the answer? Please

Cassie is traveling 675 miles today to visit her brother and his family. so far, she has stopped for gas three times. at the first stop, she put in 7.1 gallons of gas and paid $23.79. at her second stop, she put in 5.8 gallons of gas and paid $19.08. and, at the third stop, 6.6 gallons and paid $20.39. at which stop did casey pay the most for gas?

What is the average rate of change for this function for the interval from x=2 to x=4 ?

Leslie started last week with $1200 in her checking account. during the week, she wrote the checks below.