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If the interest rate is 13% compounded semi-annually made on the account, and the obligations are given below:

Deposit of $13,521 at the end of 3 and a half years.

withdrawal of $20,812 at the end of 5 years.

Semi-annual deposit of a perpetuity of $1,200 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?