A diagram will help us model this trip.

Next, we create a table to organize the information. We know the total distance is 51 miles. We are looking for the rate of speed for each part of the trip. The rate while biking is 1.6 times the rate of running. If we let r = the rate running, then the rate biking is 1.6r.
The times here are given as clock times. Cruz started from home at 6:00 a.m. and started biking at 7:30 a.m. So he spent 1.5 hours running. Then he biked from 7:30 a.m until 9:45 a.m. So he spent 2.25 hours biking.
Now, we multiply the rates by the times.

By looking at the diagram, we can see that the sum of the distance running and the distance biking is 255 miles.
|
|
|
 |
| Translate to an equation. |
 |
| Solve this equation. |
 |
| Check. RunBike10mph(1.5hours)16mph(2.25hours)==15mi−−36mi51mi |
|