Answer:
0.0975 or 9.75%
Step-by-step explanation:
Assuming that no engines fail simultaneously, the probability that exactly one engine fails is the probability that the first engine fails (15%) multiplied by the probability that the second engine does not fail (100% - 35%):

The probability of exactly one engine failure is 0.0975 or 9.75%
Multiply the 2 numbers by how long she spoke