Define a variable and write each phrase as an algebraic expression, six feet less than the width

Answer these questions showing your work plz

Factor completely. 4p^2 + 36p + 81 express the answer in the form (ap + b)^2

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?