math
posted by A .
A circular coffee table has a diameter of 5 ft. What will it cost to have the
top refinished if the company charges $3 per square foot for the refinishing?
$15.00?

Nope.
You need to find the area of the circle.
A = pi * r^2
A = 3.14 * 2.5^2
A = ?
Multiply your answer by #3.
What do you get? 
$23.55?
or would i take the 2.5^2 and multiply it getting 5 then multiply that by 3.14 which is 15.7 multiplied by 3 equals 47.10 
A = pi * r^2
A = 3.14 * 2.5^2
A = ?
2.5 squared = 6.25
A = 3.14 * 6.25
A = 19.625 square feet
$3 * 19.625 = $58.875
Since the company probably rounds up the square feet, your cost would probably be $60.00.