Conversions
You need 2 conversions
1. 1 hour = 60 minutes. 10 hours = 10 * 60 = 600 minutes.
2. 39 minutes requires no conversion. It is just 39 minutes.
3. 1 minutes contains 60 seconds. Set up a proportion
1 minute contains 60 seconds
x minute contains 24 seconds.
1/x = 60/24 Cross multiply
24 = 60x Divide by 60
24/60 = x
x = 0.4 minutes
Add (1) + (2) + (3) together.
Saturn requires 600 + 39 + 0.4 = 639.4 minutes to complete 1 revolution