Precalculus (6th Edition) Blitzer

The amount that will be received after 20 years is $\$19,129$and the interest that will be received is$\$8729$ dollars.
We plug in: $P=520,r=0.06,n=1,t=20$ Therefore, \begin{align} & A=\frac{520\left[ {{\left( 1+\frac{0.06}{1} \right)}^{1\cdot 20}}-1 \right]}{0.06} \\ & A=\frac{520\left[ {{\left( 1.06 \right)}^{20}}-1 \right]}{0.06} \\ & A\approx \19,129\\\end{align}$The interest is equal to the value of annuity minus total deposit. Thus,$\begin{align} & \text{Interest}\approx \$19,129-\$520\cdot20\\&\approx\8729\end{align}