Writing an Algebraic Expression - Part 7

Question

A car rental agency charges a base rate of $15 per day plus $0.20 per mile. Which formula could a person use to determine how much he would pay? (The variable d represents the number of days, the variable m represents the number of miles traveled, and the variable c stands for the total cost.)

Answer 1

Use the slope-intercept form of the equation of a line, which is y = mx + b. The value of m is the slope, and b represents the y-intercept. When using a linear equation to model a word problem, the flat/base rate or initial condition is the y-intercept. The rate per hour (or other unit of measurement) is the rate of change, or slope. For this problem, the equation could be written as C = 15d + 0.20m. In this case, both the number of days and the number of miles may change.