math question below

Question

Jason went to a department store. There were few people in the

department store. So, Jason conducted a simple experiment. If Jason

stood on an operating escalator, it took 12 seconds for him to reach the

top of the escalator. If Jason walked up the escalator when it was not

operating, it took 20 seconds for him to reach the top of the escalator.

If Jason walked up the operating escalator, how long would it take

him to reach the top of the escalator, rounded to the nearest tenth?

Suppose the reverse switch of the escalator were turned on so that it

was moving downward with a constant speed. If Jason stood on the

operating escalator, it took 30 seconds for Jason to reach the bottom

from the top of the escalator. If Jason walked up the operating

escalator, how long would it take him to reach the top from the

bottom of the escalator, rounded to the nearest tenth?

Answer 1

12 seconds by escalator

20 seconds walking

how long when walking up the escalator?

1/12 + 1/20 = 1/b

multiply by least common denominator

10b + 6b = 120

16b = 120

b = 120/16 = 30/4 = 15/2 = 7 1/2 seconds

when both walking & using the escalator