Randall S. answered • 09/15/20

Experienced HS/college math tutor

simple interest = principal * rate (as a decimal) * time (in years)

799 + (6.25% of 799) + (26.2% simple interest for 90 days)

= 799 + (.0625 * 799) + ( 799 * 0.262 * 90/365 )

= 799 + 49.94 + 51.62

= 900.56

her interest is 0.262*90/365 = 6.46% for the first 90 days. if you simplify the notion that 90 days is almost 3 months, then she has 9 months left, paying 3% each month. (but if 90 days falls short of 3 months, she gets hosed for another partial month and another 3%.)

6.46% + (3% * 9)

= 6.46% + 27%

= 33.46% equivalent simple interest.