since the investment is losing 10%, let's plug that in the compound interest equation but with a negative rate of 10%.
[tex]~~~~~~ \underset{\textit{with a negatie rate}}{\textit{Compound Interest Earned Amount}} \\\\ A=P\left(1~~ - ~~\frac{r}{n}\right)^{nt} \quad \begin{cases} A=\textit{accumulated amount}\\ P=\textit{original amount deposited}\dotfill &\$4000\\ r=rate\to 10\%\to \frac{10}{100}\dotfill &0.10\\ n= \begin{array}{llll} \textit{times it compounds per year}\\ \textit{six times} \end{array}\dotfill &6\\ t=years\dotfill &t \end{cases}[/tex]
[tex]A=4000\left(1~~ - ~~\frac{0.10}{6}\right)^{6\cdot t}\implies A=4000\left( \frac{59}{60} \right)^{6t}[/tex]
