Answer: 15 hours
Explanation:
2/5 & 1/4 have correlation to each other.
Divided both by two so you know how long it takes to complete 1/5 of the project.
(2/5)*0.5 , (1/4)*0.5 ; 1/5 = 1/8
Multiply both fractions by 5 to see how long it will take for the whole project.
(1/5)*5 = (1/8)*5 ; 1 = 5/8
5/8 is the amount of time in a day the whole project took so you multiply this by 24 hours.
(24/8)*5 = 15
15 hours