Determine the principle p that must be invested at rate r=8%, compounded monthly, so that $500,000 will be available for retirement in t=9 years. round to nearest cent.

Let’s say you have 2/3 + 4/5 you have to make the bottom number the same. so 3 and 5 both go into 15 so it’s
2/3 4/5

/15 /15

then to get from 3 to 15 you times it by 5 so you also times the 2 by 5. and to get from 5 to 15 you times it by 3 so you times 4 by 3.
10/15 + 12/15 = 1 7/15