Question 909816
{{{3/(9/2) = 2/3}}} 2/3 of job left undone
{{{(2/3)/6 = 1 /x}}} x = 9hr, John Alone
{{{1/9 + 1/x = 1/(9/2)}}} 
{{{1/9 + 1/x = 2/9}}} |Multiplying thru by 9x so as all denominators = 1
   x + 9 = 2x
 9hr = x, His Father alone