Shamrock Inc. was supposed to receive a payment of $$17,000,4$ years ago, and $$3,500,2$ years ago, from a customer who could not make either payment as scheduled. If the customer would like to settle both payments today, what amount would he have to pay Shamrock Inc. if interest of $3\mathrm{.}18\%$ compounded semi$-$annually is charged? Use 'today' as the focal date.