## Elementary Algebra

Recall the following rule: $\frac{a}{b} \div \frac{c}{d}=\frac{a}{b} \times \frac{d}{c}$. We convert the decimal into a fraction for the ease of simplification: $7.14\div2.1$ =$\frac{714}{100}\div\frac{21}{10}$ =$\frac{714}{100}\times\frac{10}{21}$ =$\frac{714}{10}\times\frac{1}{21}$ =$\frac{102}{10}\times\frac{1}{3}$ =$\frac{34}{10}\times\frac{1}{1}$ =$3.4$