<PRE><B>Question 407642</B>
A printing company purchased a new copier that is twice as fast as the old copier.
 With both copiers working at the same time, it takes 10 hours to do a job.
 How long would it take the new copier working alone
:
Let t = time required by the new copier working alone
then
2t = time required by the old copier alone
:
Let the completed job = 1
:
A typical shared work equation:
:
{{{10/t}}} + {{{10/(2t)}}} = 1
Multiply by 2t, results
2(10) + 10 = 2t
30 = 2t
t = {{{30/2}}}
t = 15 hrs the new copier working alone
:
:
:
Check this:
10/15 + 10/30 = 
2/3 + 1/3 = 1; confirms our solution of t = 15</PRE>