After 1 year, the initial investment increases by 7%, i.e. multiplied by 1.07. So after 1 year the investment has a value of $800 × 1.07 = $856.
After another year, that amount increases again by 7% to $856 × 1.07 = $915.92.
And so on. After t years, the investment would have a value of .
We want the find the number of years n such that
Solve for n :