Chapters to-do

[oliszymanski]

• simple interest (ch. 1)
• compound interest (ch. 2)
• commercial discount (ch. 3)
• annuities (chapters 4 as well as 1)
• debt repayment (ch. 5)
• investment appraisal metrics (ch. 6)
• random interest rate (ch. 7)
• derivative intruments (ch. 8)