Answer: 1 minute 34 seconds
Explanation:
From the question, Frankie was practicing for a 5 kilometer race and his normal time is 31 minutes and 24 seconds but yesterday he used 29 minutes and 50 seconds. To calculate how much time came of his normal time, we are going to find the difference between the yesterday's time and normal time. This will be:
31 minutes 24 seconds - 29 minutes 50 seconds = 1 minute 34 seconds