Instead of subtracting 6 from 12 then dividing they added 6 to 12 & ended up with 18. 18 by 2 is 9.
the more years the money stays invested, the more interest it earns, so clearly, if the compounding cycle is the same for both options, and the rate of 7% is the same as well for both, then the one with more years will give more interest..
so depends on what "best" means in this context, but if it's more interest earned, 3 years gives more interest than 2 years of course.
Not readable for me to be able to answer.
