Chapter 4 - Inverse, Exponential, and Logarithmic Functions - 4.5 Exponential and Logarithmic Equations - 4.5 Exercises - Page 469: 33

$\{ 2011.568\}$

Step 1. Rewrite the equation as $(1.015)^{x-1980}=\frac{8}{5}$ Step 2. Take natural logarithm on both sides to get $(x-1980)\ ln(1.015)=ln\frac{8}{5}$, thus $x=1980+\frac{ln\frac{8}{5}}{ ln(1.015)}\approx2011.568$ Step 3. Write answer in set form $\{ 2011.568\}$