Please? im so confused

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?

Which of the following is most likely the next step in the series? a3z, b6y, c9x, d12w, е15v, f18u

The distributive property allows you to say that 3(x − 1) = 3x −