For this question you must work out the fraction in a decimal
For example 1/2 can be written as 0.5.
Using this we can work out:
1 1/2 = 1.5
2 1/2 = 2.5
(The whole numbers stay the same)
Knowing this, we can work out the hours Mary spent running in which we add up all the hours:
1.5 + 2 + 2.5 + 3
And this will all add up to: 9
Answer = 9
Hope this helped!