[" Examplifil A circular racetrack of radius "30m" is banked at an angle of "15^(@)." If the coefficient "],[" of friction between the whels of a race cand the road is "0.2" ,what is the "(a)" optimum speed of the "],[" race car to avoid wear and tear on its tyres,and (b) maximum permissible speed to avoid slipping? "]