Algebra 1

$\frac{4}{5}$
When we are taking the square root of something, we want to find what number, when squared, is equal to the number under the square root symbol. $(\frac{4}{5})(\frac{4}{5})=\frac{16}{25}$ Therefore, it follows that: $\sqrt {\frac{16}{25}}=\frac{4}{5}$