## Functions Modeling Change: A Preparation for Calculus, 5th Edition

$x\approx38.376$
Take the $\ln$ of both sides to get $$\ln e^{0.12x}=\ln 100$$ Since $\ln e^a=a$ for all positive $a$, this simplifies to $$0.12x=\ln 100$$ Dividing both sides by $0.12$ yields $$x=\frac{\ln 100}{0.12}\approx38.376$$