Question

Reggie can line a football field in 120 minutes. Rosalinda can line a football field in 80 minutes. If they work together, how many minutes does it take them to line a football field?
a. 40 minutes
b. 80 minutes
c. 200 minutes
d. 240 minutes HELP?!

Answer 1

Answer:

If they work together, they take 48 minutes to line the football field.

Step-by-step explanation:

Given: Reggie can line a football field in 120 minutes.  Rosalinda can line a football field in 80 minutes.  

To find : If they work together, how many minutes does it take them to line a football field?

Solution :

If they work together,

Let the number of minutes(x) they take to line the foot ball field.

According to question,

$\frac{1}{x}=\frac{1}{120}+\frac{1}{80}$

$\frac{1}{x}=\frac{80+120}{120\times 80}$

$\frac{1}{x}=\frac{200}{120\times 80}$

Cross multiply,

$x=\frac{120\times 80}{200}$

$x=12\times 4$

$x=48$

Therefore, If they work together, they take 48 minutes to line the football field.

Answer 2

Answer:  If they work together, they can line a football field in 48 minutes.

Step-by-step explanation:  Given that Reggie can line a football field in 120 minutes and Rosalinda can line a football field in 80 minutes.

We are to find the number of minutes does it take them to line a football field if they work together.

We have

Time taken by Reggie to line a football field = 120 minutes.

So, in 1 minute, Reggie can line $\dfrac{1}{120}$ part of the field.

Time taken by Rosalinda to line a football field = 80 minutes.

So, in 1 minute, Rosalinda can line $\dfrac{1}{80}$ part of the field.

Therefore, if they work together, the portion of the football field that they can lie in 1 minute is given by

$\dfrac{1}{120}+\dfrac{1}{80}\\\\\\=\dfrac{2+3}{240}\\\\\\=\dfrac{5}{240}\\\\\\=\dfrac{1}{48}$

Thus, if they work together, they can line a football field in 48 minutes.