simple interest is where 3% of the original value is added on each year
goal number = $102
original number = $680
3% of $680 can be found by getting 1% and multiplying by 3
100% = original number = $680
100% / 100 = 1% so $680 / 100 = $6.80 = 1%
3% = $6.80 * 3 = $20.40
so each year the money rises by $20.40
to find out how many years it would take to get to $102:
$102 / $20.40 = 5 years