Chapter 1 - Section 1.1 - Introduction to Algebra: Variables and Mathematical Models - Exercise Set - Page 13: 110

$\dfrac{10}{21}$

Let $a=2,$ $b=3,$ $c=7,$ and $d=5.$ Since the given formula states that $\dfrac{a}{b}\div\dfrac{c}{d}=\dfrac{a\cdot d}{b\cdot c},$ then \begin{array}{l}\require{cancel} \dfrac{2}{3}\div\dfrac{7}{5} \\\Rightarrow \dfrac{2\cdot 5}{3\cdot 7} \\\Rightarrow \dfrac{10}{21} .\end{array}