Write the equation of a line with a slope of 4 and a y-intercept of -3

The depth of a lake at a certain point, wich is a function of the distance of that point from shore, is 30 feet.

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?

Explain how you can use the associative property to evaluate (7x50)x4.