Question 670005
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Hi,
A pipe can fill a tank in 10 hours. 
If a second pipe is opened, the two pipes together can fill the tank in 6 hours. 
How long {{{highlight(x)}}}would it take the second pipe alone to fill the tank?
Translate into an equation: PER hr KEY
{{{ 1/10 + 1/x = 1/6 }}}   |Multiplying thru by 60x so as all denominators = 1
   6x + 60 = 10x
        60 = 4x
         15hr = x