Question 218910
Andrew takes eighteen hours to complete a certain project alone.
 he had worked six hours on the project when Dylan joined him to finish the project. 
Together they finished the project in six more hours. 
How many hours does it take for Dylan to complete the entire project alone?
:
Let t = time required by Dylan alone
:
Let the completed job = 1
:
Andrew will work a total of 12 hrs
:
{{{12/18}}} + {{{6/t}}} = 1
Multiply equation by 18t, results:
12t + 18(6) = 18t
12t + 108 = 18t
108 = 18t - 12t
108 = 6t
t = {{{108/6}}}
t = 18 hrs is D's time alone also