Betty can mow a lawn in 60 minutes. Melissa can mow the same lawn in 30 minutes. How long does it take for both Betty and Melissa to mow the lawn if they are working together? Express your answer as a reduced fraction.

  20 minutes

Step-by-step explanation:

Melissa works as fast as two Bettys, so working together, they get the job done at the rate 3 Bettys could do it. That time is (60 minutes)/3 = 20 minutes.

Working together, Betty and Melissa can mow the lawn in 20 minutes.

You can also think in terms of mowing rates as lawns per minute. The total mowing rate is ...

  Betty's rate + Melissa's rate = (1/60 lawns/min) +(1/30 lawns/min)

  = (1/60 +2/60) lawns/min = 1/20 lawns/min

The inverse rate is then ...

  20/1 min/lawn

Together, they take 20 minutes to mow 1 lawn.

arithmetic sequence

step-by-step explanation:

given that a sequence has terms as

19, 15, 11,

this is represented on a graph

the pattern indicates that the sequence is an arithmetic sequence with i term

a=19 and common difference d =-4

any general term

thus the sequence is reduced by 4 for each successive term starting from 1 and nth term is

24-5n.

first negative term would start after 5th term

5th term =24-25< 0

from 5th term onwards the sequence would be negative.

step-by-step explanation:

f