Admission to a circus is $16 for adults and $8 for children . write an expression to find the total cost of 3 adult tickets and 8 chidern's ticket. then find the total cost

Amass weighing 16 pounds stretches a spring 8/3 feet. the mass is initially released from rest from a point 2 feet below the equilibrium position, and the subsequent motion takes place in a medium that offers a damping force that is numerically equal to 1/2 the instantaneous velocity. find the equation of motion if the mass is driven by an external force equal to f(t)=cos(2t).