Chapter 7 - Exponents and Exponential Functions - 7-1 Zero and Negative Exponents - Practice and Problem-Solving Exercises - Page 418: 41

$\frac{4}{5}$

We start with the given expression: $4s^{-1}$ The negative exponent rule states that for every nonzero number $a$ and integer $n$, $a^{-n}=\frac{1}{a^n}$. We use this rule to rewrite the expression: $\frac{4}{s}$ We plug in the value of $s$: $\frac{4}{5}$