Answer:
4.875 billion hours
Explanation:
-Let X be the total time spent on taxes and 7.8 billion (80%) is time on paper work.
#We equate and cross multiply to get the total time on taxes:

-let y be the 50% amount of time spent. we equate to find it in actual hours:

Hence, 50% of the time is equivalent to 4.875 billion hours