Answer:
36 miles.
Step-by-step explanation:
We have been given that Karina rode her bike up a mountain trail at an average of 4 mph. Then she rode it back down the trail at an average of 20 mph. The entire trip took 3 hours.
[tex]\text{Distance}=\text{Speed}\times \text{Time}[/tex]
Substitute the given values:
[tex]\text{Distance}=(\frac{4\text{ miles}}{\text{Hour}}+\frac{20\text{ miles}}{\text{Hour}})\times 3\text{ Hours}[/tex]
[tex]\text{Distance}=(\frac{24\text{ miles}}{\text{Hour}})\times 3\text{ Hours}[/tex]
[tex]\text{Distance}=24\text{ miles}\times 3[/tex]
[tex]\text{Distance}=72\text{ miles}[/tex]
The total distance is 72 miles, so the distance going up would be half of 72.
[tex]\frac{72}{2}=36[/tex]
Therefore, Karina went 36 miles up the mountain.
