SOLUTION: 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

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Question 273718: 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?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
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%2Fx + 20%2F%282x%29 = 1
which is:
8%2Fx + 10%2Fx = 1
multiply byx, results:
8 + 10 = x
x = 18 hrs, the experience guy working alone
:
:
Check solution
8%2F18 + 20%2F%2836%29 = 1
.44 + .56 = 1