# Algebra problem

• Nov 6th 2008, 06:17 PM
lila
Algebra problem
A computer expert can do a job in 6 hours. His secretary can do the same job in 7hrs. After the expert works on the job foe 2 hours, his secretary takes it and complete the job. How many hrs did it take her to complete the job?

after 2hrs the experthad completed 1/3 of the job...what do I have to do now?? 1/3 * 1/7
..I'm not sure...Could someone help me??? Please.
• Nov 6th 2008, 06:39 PM
Soroban
Hello, lila!

Quote:

A computer expert can do a job in 6 hours.
His secretary can do the same job in 7 hrs.
After the expert works on the job foe 2 hours,
his secretary takes over and complete the job.
How many hrs did it take her to complete the job?

The secretary can do the job in 7 hours.
In one hour, she completes $\displaystyle \tfrac{1}{7}$ of the job.
In $\displaystyle x$ hours, she completes $\displaystyle \tfrac{x}{7}$ of the job.

The expert has already completed $\displaystyle \tfrac{1}{3}$ of the job.
The secretary will complete the other $\displaystyle \tfrac{2}{3}$ of the job.

There is our equation: . $\displaystyle \frac{x}{7} \:=\:\frac{2}{3} \quad\Rightarrow\quad x \:=\:\frac{14}{3}$

It took her $\displaystyle 4\tfrac{2}{3}$ hours to complete the job.

• Nov 6th 2008, 06:50 PM
lila
Thank you Soroban