2commercial for every 10 songs what is the unit rate of songs to commercials?

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?

Equation for the calculation double 2 and then add 5

Solve the equation by completing the square. x^2+2x=17