If the interest rate is 13% compounded semi-annually made on the account, and the obligations are given below: Deposit of P13,521 at the end of 3 and a half years. Withdrawal of P20,812 at the end of 5 years. Semi-annual deposit of a perpetuity of P1,200 starting at the end of 6 and a half years.

Determine the following:

a.) Present value of all the obligations made on the account.

b.) Additional amount of withdrawal at the end of 5 years to balance the cash flows.