A red car is traveling at 55 mph. A blue car is traveling at 65 mph. The cars are 305 miles apart. The cars started at the same spot at different times. The total driving time for the two cars is 5 hours. Which system of equations could be used to solve for the total driving time of the red car (r) and the total driving time of the blue car (b)?
Let r be the total driving time of the red car and b be the total driving time of the blue car. The equation that represents the total distance driven by the red car would be 55r, and the equation that represents the total distance driven by the blue car would be 65b. Since the total distance the cars traveled is 305 miles, the equation that represents that relationship would be 55r + 65b = 305. Finally, since the total driving time for the two cars is 5 hours, the equation that represents that relationship would be r + b = 5. Thus, the system of equations is:
55r + 65b = 305
r + b = 5