word problem.

Question

two clerks are adressing envelopes for a mayoral candidates political campaign. One clerk can address one envelope every 30 s, whereas it takes 40 s for the second clerk to address one envelope. How many minutes will it take them, working together, to address 140 envelopes?

Answer 1

Restate these as rates:

One clerk can do 120 per hour, the other can do 90 per hour. Together they can do

120 + 90 = 210 per hour.

It will take 140/210 = 2/3 hour to do 140.

2/3 hour = 40 minutes