Final answer:
To build 2 and a half walls, it would take approximately 28.8 hours.
Step-by-step explanation:
To build 1 wall, it takes 24 hours of work. To calculate how many hours it would take to build 2 and a half walls, we need to find one-fifth of 24 hours since 1/5 represents half a wall. One-fifth of 24 is 4.8 hours, so it would take approximately 4.8 hours to build half a wall. Adding this to the original 24 hours, it would take around 28.8 hours to build 2 and a half walls.
Learn more about Calculating the number of hours to build multiple walls