What if your heart rate r in beats per minute is the number of times h 15 seconds multiplied by 4 given write an equation to find r?
```
r = 4 * (h / (15/60))
```
Simplifying the equation:
```
r = 4 * (h / 0.25)
```
```
r = 16 * h
```
Therefore, the equation to find the heart rate r in beats per minute is r = 16h, where h represents the number of heartbeats counted in 15 seconds.