use the formula for interest compounded in n periods per year
[tex]A=P\cdot(1+\frac{r}{n})^{nt}[/tex]where n should 12 since it is compounded monthly
[tex]\begin{gathered} A=20,000\cdot(1+\frac{0.065}{12})^{12\cdot40} \\ A=267,392.05 \end{gathered}[/tex]