Find the quotient:5÷1/5?

First, you find the reciprocal of $\frac{1}{5}$. The reciprocal of the fraction is found by flipping it, so this one is $\frac{5}{1}$. Then you multiply instead of dividing, which is $5 \times 5$, which is $25$.
$5 \div \frac{1}{5} = 5 \times \frac{5}{1} = 25$