Answer :
Answer:
[tex]r_{w}*t + r_{r}*t = 2 jobs\\ \frac{1}{40} *t + \frac{1}{120} *t = 2[/tex]
Step-by-step explanation:
Given are the time it takes for each worker (Wilma and Rocky) to mow one lawn.
To derive a formula to be able to find the time it takes if they work together we first need to find the rate of work of each worker
The basic formula for rate of working is as follow
[tex]rate(r) = \frac{Job}{time}[/tex]
Lets calculate the rate of work for Wilma and Rocky
Wilma
[tex]r_{w} = \frac{1}{40}[/tex]
Rocky
[tex]r_{r} = \frac{1}{120}[/tex]
Notice the 1 at the numerator, this is because the times are given for one job.
To complete two jobs together we derive the following formula based on adding their rates together
[tex]r_{w}*t + r_{r}*t = 2 jobs\\ \frac{1}{40} *t + \frac{1}{120} *t = 2[/tex]