A privately owned liquor store operates both a drive-in facility and a walk-in facility. On a randomly selected day, let X and Y , respectively, be the proportions of the time that the drive-in and walk-in facilities are in use, and suppose that the joint probability density function of these random variables is given by:

f(x, y) {2/3(x+2y), 0 <= x <= 1, 0<= y <= 1
{0, elsewhere

a. Find the marginal density of x
b. Find the marginal density of y
c. Find the probability that the drive-in facility is busy lessthan one-half of the time.