A carpenter can do a job in eight hours. His assistant can do the same job in ten hours. How long would it take them to do the job together?

it will take them about 4.44 hours to complete the job when they work together

Step-by-step explanation:

If carpenter B can complete the job in 8 hours, then the portion (fraction) of the job done in the unit of time (one hour) by this carpenter is 1/8

The assistant A can complete the same job in 10 hours, so the fraction of the job done by him in one hour is: 1/10

When they work together, we don't know what time it will take (we name it "x" hours). Therefore the fraction of the job dome in these x hours would be: 1/x

Now we can set the equation that says that the fraction of the job done by B in the unit of time plus the fraction done by A should equal the fraction completed when they work together:

Therefore, it will take them about 4.44 hours to complete the job when they work together.

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step-by-step explanation:

hopefully im right