Simplify (3^-2/3•3^1/3)^-1 using rational exponents

Charles is on a 8 1/2 mile bike ride. he stops for a rest after he’s gone 5 2/5 miles. how much farther does he still have to go?

The center of a circle represent by the equation (x+9)^2+(y-6)^2=10^2 (-9,6), (-6,9), (6,-9) ,(9,-6)

Awater tank holds 18000 gallons. how long will it take for the water level to reach 6000 gallons if the water is used at anaverage rate of 450 gallons per day