Algebra 2 Common Core

$$4$$
First, find and divide out any common factors: $$\frac{7x}{8}\times \frac{64}{14x}=\bigg(\frac{7\times x}{8}\bigg)\times \bigg(\frac{8\times 2\times 2\times 2}{2\times 7\times x}\bigg).$$ In this case, cancel the factors $7$, $x$, $8$, and $2$ and the result is $$2\times 2=4.$$