Answer:
-9.85
Step-by-step explanation:
-15.5 - 4.2 = -19.7
Negatives work like positives
19.7 / 2 = 9.85
Turn that into a negative
-9.85
If his heart rate slows down then he needs to continue doing what he's doing to keep his heart rate steady
<u>Equation given</u>: 
- S: distance fallen --> 1279 ft
- t: time taken for the distance fallen
<u>Solve</u>:

Thus it took <u>8 seconds</u> for the thing to fall from the top
Hope that helps!