How long would it take them to deliver the newspapers if they work together?

Question

please explain step by step, i do want to learn

Trent can deliver his newspapers in 30mins. It takes Lois 20 mins to do the same route. How long would it take them to deliver the newspapers if they work together?

Answer 1

Trent can do 1/30 of the route in a minute
Lois can do 1/20 of the route in a minute
Together they can do 1/30 + 1/20 of the route in a minute
1/30 + 1/20 = 2/60 + 3/60 = 5/60 = 1/12

Together they can do 1/12 of the route in a minute, so it takes them 12 minutes.

Answer 2

12 minutes.