Question

Lisa takes 3 hours to mow the lawn, while her cousin, Barb, takes 2 hours. How long will it take them working together?

Answer 1

Answer:6 hours

Step-by-step explanation:

3x2=6

Answer 2

Answer:

t=72 minutes

Step-by-step explanation:

If it takes Lisa 3 hours to mow the lawn, then she mows 13 of the lawn per hour. Barb takes 2 hours to do it alone so she completes 12 of the lawn each hour. Working together, they mow the lawn in some time t. This can be written as

$\frac{1}{3}$+$\frac{1}{2}$=$\frac{1}{t}$

Multiply each side by the least common denominator, 6t.

6t($\frac{1}{3}$+$\frac{1}{2}$)=6t($\frac{1}{t}$)

Simplify and solve.

2t+3t=6

We can multiply the fraction by 60 to convert the fraction of an hour to minutes.  

t=$\frac{6}{5}$ (60 minutes)

To mow the lawn, it takes the two working together

t=72 minutes.