Hello, could someone me out with these questions?
it takes 8 hours for one crew to clean an office building. it takes a second crew 10 hours to clean the same building. if the first crew works 2 hours and leaves and the second crew takes over to complete the job, how long will it take the second crew to finish cleaning the building?
two rsm students are standing 20ft apart and spot mrs. rifkin. if they immediately run opposite directions with speeds of 300ft/min and 200ft/min, how many minutes will pass until they are 3,000ft apart?

  1.  7.5 hours

  2.  5.96 minutes

Step-by-step explanation:

1.  In 2 hours, the first crew will have completed 2/8 = 1/4 of the work. The second crew will need 3/4×10 hours = 7.5 hours to complete the work.

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2.  The two students are separating at the rate of (300 + 200) ft/min = 500 ft/min. They will add 2980 ft to their initial 20 ft separation in ...

  2980 ft/(500 ft/min) = 5.96 min

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.