For a certain automobile, Upper M left parenthesis x right parenthesis equals negative 0.015 x squared plus 1.46 x minus 7.5M(x)=−0.015x2+1.46x−7.5, 30 less than or equals x less than or equals 6030<=x<=60, represents the miles per gallon obtained at a speed of x miles per hour. (a) Find the absolute maximum miles per gallon and the speed at which it occurs. (b) Find the absolute minimum miles per gallon and the speed at which it occurs