Question 1199453
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Lynn works twice as fast compared to Farrah.
This means Lynn does 2/3 of the work when they team up.
Farrah does the remaining 1/3.
Note that 2/3 is twice that of 1/3; also the two fractions add to 1.


Consider a tank that is 24 gallons. You can pick any other multiple of 3.


Since Lynn does 2/3 of the work, she is able to fill (2/3)*24 = 16 gallons in 2 hours.
Her unit rate is 16/2 = 8 gallons per hour.
If Lynn worked alone, then she needs 24/8 = 3 hours to do the full job.


Relevant useful formulas
rate = (amount done)/(time)
time = (amount done)/(rate)


Farrah does 1/3 of the 24 gallons, so she fills (1/3)*24 = 8 gallons in 2 hours.
rate = 8/2 = 4 gallons per hour
If Farrah worked alone, then she would need 24/4 = 6 hours.
Or note that since Lynn takes 3 hours, Farrah would take 2*3 = 6 hours since Farrah works for twice as long.


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Answers:
Lynn = <font color=red>3 hours</font>
Farrah = <font color=red>6 hours</font>
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