I don't understand this. Please thoroughly explain. I$\text{'}$m trying to complete with paper and pencil. Please fully explain how I show calculate not understanding how.

P$15-13$ Lockbox system Eagle Industries believes that a lockbox system can shorten its accounts

receivable collection period by three days. Credit sales are $$3,240,000$ per year, billed on a

continuous basis. The firm has other equally risky investments that earn a return of $15\%.$ The cost

of the lockbox system is $$9,000$ per year. $($Note: Assume a $365-$day year.$)$

a$.$ What amount of cash will be made available for other uses under the lockbox system?

b$.$ What net benefit $($cost$)$ will the firm realize if it adopts the lockbox system? Should it adopt the

proposed lockbox system?