Answer:
48 minutes
Step-by-step explanation:
Given that;
Rosalinda can line the football field in 80 minutes
Reggie can line the football field in 120 minutes
Lets assume that if they work together, they will take T minutes to line the football field
Hence;
Thus in 1 minute, Rosalina can line 1/80 of the field where as Reggie can line 1/120 of the field
![\frac{1}{T} =\frac{1}{120} +\frac{1}{80} \\\\\frac{1}{T} =\frac{2+3}{240}\\\\](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7BT%7D%20%3D%5Cfrac%7B1%7D%7B120%7D%20%2B%5Cfrac%7B1%7D%7B80%7D%20%5C%5C%5C%5C%5Cfrac%7B1%7D%7BT%7D%20%3D%5Cfrac%7B2%2B3%7D%7B240%7D%5C%5C%5C%5C)
The sum of the two fractions will represent the size of the field that can be lined in 1 minute.
![\frac{1}{T} =\frac{5}{240} \\\\\frac{1}{T} =\frac{1}{48} \\T= 48](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7BT%7D%20%3D%5Cfrac%7B5%7D%7B240%7D%20%5C%5C%5C%5C%5Cfrac%7B1%7D%7BT%7D%20%3D%5Cfrac%7B1%7D%7B48%7D%20%5C%5CT%3D%2048)
The reciprocal of the sum of the two fractions will represent the time taken for both Rosalinda and Reggie to line the field.
Answer ; It will take them 48 minutes for them to line the football field