Question

The runners time to complete the marathon was 10% less than the time to complete the last marathon. (Please see attached photo)

Answer 1

Let's say that last marathon was completed in a time t. This represents the total ammount.

Now if current marathon was completed in 10% less time we can write:

10% = 0.1

Then we can do a simple calculation:

t - 0.1 t = 0.9 t = 90% of t

So the time to complete this marathon is 90% of the time of last marathon.