<PRE><B>Question 273718</B>
An experienced bricklayer can work twice as fast as an apprentice bricklayer.
 After they worked on a job for 8 hours, the experienced bricklayer quit.
 The apprentice required 12 more hours to finish the job.
 How long would it take the experienced bricklayer, working alone, to do the job?
:
Let x = time required by an experienced bricklayer alone
then
2x = time required by an apprentice alone
:
Let the completed job = 1
:
Experienced worked for 8 hrs
Apprentice worked 8 + 12 = 20 hrs
:
{{{8/x}}} + {{{20/(2x)}}} = 1
which is:
{{{8/x}}} + {{{10/x}}} = 1
multiply byx, results:
8 + 10 = x
x = 18 hrs, the experience guy working alone
:
:
Check solution
{{{8/18}}} + {{{20/(36)}}} = 1
.44 + .56 = 1</PRE>