Question 619812
  <pre><font face = "Tohoma" size = 3 color = "indigo"><b> 
Hi,
two hoses are working together to fill a swimming pool.
one of the hoses can fill the pool alone in 7 hours the other can fill the pool alone in 12 hours 
how long  {{{highlight(x)}}}   would it take both hoses to fill the pool together?
  PER hr KEY
 1/7 + 1/12 = 1/x   |Multiplying thru by 84x so as all denominators = 1
  12x + 7x = 84
    19x = 84
      x = 4.42 hr