Question

A firm advertises for workers to address envelopes. Priscilla says she will work 100 hours. Herb will work for 80 hours. If each can address 10,000 envelopes in the time they work, how long would it take them to address 10,000 envelopes if they work together?

i am lost, can you show steps with the answer

Answer 1

If they take x hours together,

1/x = 1/100 + 1/80

This is just a typical work problem. Forget the 10,000 envelopes. It's just 1 job. P can do 1/100 of the job in an hour, and H can do 1/80. So, add up the amounts they do.