Tell me how to do it and why

It would take them 6.667 minutes to paint 50 square feet together.

Step-by-step explanation:

This is a classic work problem.  If Sam can do the job in 10 minutes, she can get done 1/10 of the job in one minute.  If you can do the job in 5 minutes, you can 1/5 of the job done in one minute.  To find out how many minutes it will take them together to paint 25 square feet, set the addition of their times equal to 1/x:

x is how long it takes them to get the job done together.  Find the common denominator and multiply it through be everything to get rid of the denominators altogether.  That denominator is 10x:

Simplify to get the simple equation x + 2x = 10 and 3x = 10.  That means that x=3 1/3.  That's how long it takes to do 25 square feet.  Double that time for 50 square feet.

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step-by-step explanation:

a)(x-2)^2+(y-1)^2=9

step-by-step explanation:

(picture explains)