A percent change implies multiplication by a growth factor.
Set up the situation as an algebra problem.

- What do you multiply by to get from [math]
2{,}000 to [math]10{,}000\text{?} [math]2{,}000 \cdot b = 10{,}000 What is the growth factor b? [math]b = - What percent increase does this represent?
[math] \%