In terms of T, what is the number of hours travelling on country roads?
1 Answer
From the time information:
Using the speed and distance information:
Solving:
Explanation:
The question is confusing in that there are two ways to find such a formula. However, that does allow you to derive an equation in
Formula based on time information given
We are told that the journey took
So the time on country roads was:
#4-T# hours
Formula calculated from distances and speeds
The distance travelled on the freeway is
So the distance travelled on country roads is
The time taken to travel that distance is given by dividing by the average speed, to get:
#(300-90T)/70 = (30-9T)/7 = 30/7-9/7T# hours.
Solve for
Given these two formulae which should give the same result, we can write:
#4 - T = 30/7-9/7T#
Add
#2/7T = 2/7#
So
That is, a total of