Final answer:
The equation that can be used to determine the total number of miles that Johanna will ride in 'h' hours is m = 8h.
Step-by-step explanation:
The equation that can be used to determine the total number of miles that Johanna will ride in 'h' hours is m = 8h.
This equation is obtained by recognizing that Johanna rode 8 miles in 40 minutes, which can be simplified to 8 miles in 2/3 hours (since 40 minutes is 2/3 of an hour).
Since Johanna rides at a constant rate, we can use the formula distance = rate x time, where the rate is 8 miles/hour (since she rode 8 miles in 2/3 hours) and the time is 'h' hours. Therefore, the equation becomes m = 8h.