a car averages 65 mph for the first 5 hours of a trip and averages 75 mph for each additional hour . the average speed for the entire trip was 60 mph . how many hours long is the trip ?
"let the time for which car averages 75 mph = t 60 * ( t + 5 ) = 65 * 4 + 70 t = > 10 t = 40 = > t = 4 total duration of the trip = 5 + 4 = 9 answer a"
add(divide(subtract(multiply(60, 5), multiply(65, 5)), subtract(75, 60)), 5)