To find 8 ×17, I double and halve

Which of the following represents the length of a diagonal of this trapezoid?

Cody ran nine miles on his first day of training. the next day he ran 1/8 that distance. how far did he run the second day?

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).