As many as you can very urgent

The water has been on the stove y=9.5x+62.1 after how many minutes will the tempature be 138.1 f

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?

Math question.. plz me .. best answer all