ANSWER
6.4 hours
EXPLANATION
if it takes 10 hours to get 50%, then it will take less number of hours to get 32%
We use proportion to solve this question.
If less more divides.
The number of hours it will take to get 32% is


Hence it will take 6.4 hours to get 32%
Here you go take a look at the picture it explain what to do and the answer.
The greatest common factor of 72 and 4 is 4.
Step-by-step explanation:
I hope that is useful for you :)