Answer
$622.9$ m
Work Step by Step
let $v(t)=100-9.8t$
$\int_0^{15} |100-9.8t| dt$ = $\int_0^{\frac{100}{9.8}} |100-9.8t| dt$ + $\int_{\frac{100}{9.8}}^{15} |100-9.8t| dt$
= $(100t-4.9t^{2} |_0^{\frac{100}{9.8}}$+$(100t-4.9t^{2} |_{\frac{100}{9.8}}^{15}$
= $622.9$ m