Chapter 5 - Section 5.2 - More Work with Exponents and Scientific Notation - Exercise Set - Page 268: 75

$3.0\times10^{-1}$

Using laws of exponents, the given expression simplifies to \begin{align*} & \dfrac{0.0069}{0.023} \\\\&= \dfrac{6.9\times10^{-3}}{2.3\times10^{-2}} \\\\&= (6.9\div2.3)(10^{-3}\div10^{-2}) \\\\&= 3.0\times10^{-3-(-2)} \\\\&= 3.0\times10^{-1} .\end{align*}