Answer:
7.74 minutes
Step-by-step explanation:
Scott's rate = 20 /16 = 1.25
Ashley's rate = 20 / 15 = 1.333
Combined rate = (1.25 + 1.3333) = 2.583333
Hence, time it will take to inflate 20 balloons :
Rate = number of balloons / time taken
2.583333 = 20 / time taken
Time taken = 20 / 2.583333
Time taken = 7.7419
It will take them approximately 7.7 minutes to inflate 20 balloons
