Answer:
It takes 8 4/7 days for both bricklayers to build the wall together.
Step-by-step explanation:
The first bricklayer takes 15 days to build the wall, which means it builds 1/15 of the wall per day.
The second bricklayer takes 20 days to build the wall, which means it builds 1/20 of the wall per day.
So if they build the wall together, the expression below will tell how much of the wall they build per day together.
1/15 + 1/20
To add the fractions, we must find a common denominator, which is 60.
4/60 + 3/60, which equals 7/60.
So, they can build 7/60 of the wall per day together. How many days will it take them? We must find how many times 7 fits into 60, which can be done by solving 60/7, which is 8 4/7.
So, it takes 8 4/7 days for both bricklayers to build the wall together.
