| Word Problems: Working Together |
In order to solve problems involving working together, it is necessary to The goal of a “working together” problem is generally to figure how fast a job can be completed if two or more workers complete the job together. Suppose that it takes Janet 6 hours to paint her room if she works alone and it takes Carol 4 hours to paint the same room if she works alone. How long will it take them to paint the room if they work together?
First, we will let x be the amount of time it takes to paint the room (in hours) if the two work together.
Janet would need 6 hours if she did the entire job by herself, so her working rate is  of the job in an hour. Likewise, Carol’s rate is  of the job in an hour.
In x hours, Janet paints  of the room and Carol paints  of the room. Since the two females will be working together, we will add the two parts together. The sum equals one complete job and gives us the following equation:
We are now ready to solve this equation to determine how long it will take the two females to paint the room if they work together.
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Multiply each term of the equation by the common denominator 12 |
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Simplify |
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Collect like terms |
 hours |
Solve for x |
Remember that x represents the amount of time it takes to paint the room (in hours) if the two work together. So, working together, the two females can paint the room in only  hours or 2 hours and 24 minutes. |
Let's Practice
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As you can see, this type of problem requires that you carefully establish what x will represent. You must then set up rates for each “worker,” put the rates together using addition or subtraction to write an equation, and carefully solve using a common denominator to multiply times every term of the equation. At the conclusion of the problem, you must check for the reasonableness of your solution.
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D Saye
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