How to deal with these question

As an investment manager of Southern Cross fund, you have $10 mil in capital to purchase debt securities; $5 mil for money market securities and $5 mil for bonds. a) Telstra is selling 90-day promissory notes at a face value of $100,000 for which you require a yield of 4% per annum. What price are you willing to pay for each Telstra note and how many would you be willing to buy at that price? b) Telstra is also selling 5-year corporate bonds at a face value of $1,000,000 which pay a semi-annual coupon of 5% per annum. If you require a yield-to-maturity of 6% per annum, what price are you willing to pay for each Telstra bond and how many would you be willing to buy at that price? c) If the credit rating of Telstra improves, explain why you would be willing to pay more or less for Telstra debt securities