if the value of the stock investment decreased 20% over the last year, we can think that now we have the 80% of the initial value. So
To find the value of the stock investment a year ago, you can solve this equation:
[tex]\begin{gathered} \frac{100}{80}\cdot13000\text{ = 16250} \\ \end{gathered}[/tex]So the answer is 16250
