Assuming your plus sign means divide:
\(\frac{4}{10} / \frac{5}{10}\) becomes
\(\frac{4}{10} * \frac{8}{5}\) you flip the second fraction and multiply. To multiply you multiply across the bottom and then across the top.
\(\frac{4}{10} * \frac{8}{5} = \frac{32}{50} or \frac{16}{25} or .64\)
Hope that helps. Feel free to ask any questions.
