July 1st 2021
Investment in Bonds 775,000
Discount on Bonds investment 100,000
Cash 675,000
*********************
Discount on Bonds investment is calculated by taking the difference between 775,000 and 675,000 so it would equal 100,000
December 31st 2021
Cash $15,500
Discount on Bond investment $1,375
Interest revenue $16,875
*********************
Cash is calculated by multiplying 775,000 with 4%/2 so that it equals 15,500
interest revenue is calculated by multiplying 675,000 with 5%/2 so that is will be 16,875
then for the discount, you take the difference between the interest of what you bought the bond at 16,875 and subtract the cash coupon payment you are receiving 15,500 = 1,375
Good luck!