Answer: 0.8 (no units included)
Explanation:
D = R*T
You need to rearrange the equation in-order to find time so you'll new equation will look like this:
T = D/R
Now Solve for T
T = 16.2 kilometers / 21 kilometers per hour
T ≈ 0.7714 hours
T ≈ 0.8
So, the trip took approximately 0.8 hours.