Answer: She cycles 25% of the time
Explanation:
From the question, Sally walks 15% of the time.
She drives 3/5 of the time.
We then convert 3/5 to percentage.
Converting to percentage means multiplying by a factor of 100.
Hence, Sally drives 3/5*100 = 60% of the time.
If Sally walks 15% of the time and drives 60% of the time, adding up the percentage time used by these two media of transportation will give us
60% + 15% = 75%
Hence if she cycles for the remainder of the time, expressing it as percentage would mean subtracting the time used in other means by 100%
Hence it will be 100% - 75% = 25%