An investment initially worth $5300 earns 7.7% annual interest, and an investment initially worth $8000 earns 5.6% annual interest, both compounded annually.

How long will it take for the smaller investment to catch up with the larger one?

2 answers

solve for t in

5300 * 1.077^t = 8000 * 1.056^t
t = 20.9 years
or, 21, since the interest is credited at year's end.
where is the work? I'm still lost