Final answer:
Kelly had 3.5 minutes left for question c.
Step-by-step explanation:
To find the time Kelly had left for question c, we need to subtract the time she spent on question a and question b from the total time she had.
First, let's convert the mixed numbers to improper fractions:
11 9/10 = 119/10
4 3/5 = 23/5
Next, let's add the time she spent on each question:
(119/10) + (23/5) = (119/10) + (46/10) = 165/10 = 16 1/2 minutes
Finally, subtract the time from the total time she had:
20 minutes - 16 1/2 minutes = 20 minutes - 16.5 minutes = 3.5 minutes
Therefore, Kelly had 3.5 minutes left for question c.