Question 315935
    filling a tank through a large tube takes 30 minutes. It takes 50 minutes for the tank to fully drain through a smaller tube. how long will it take to fill the tank if both tubes are open
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Let x = time it takes to fill tank when both tubes are open
then
x(1/30 - 1/50) = 1
Multiplying both sides by 1500:
x(50 - 30) = 1500
x(20) = 1500
x = 75 minutes