There are two ways to solve this. You can either cross-multiply or find a common denominator. They're pretty similar, but you can use whichever one makes more sense to you.
Cross-Multiplying :
\(\frac{4}{5}\) = \(\frac{x}{10}\) Mutiply the numerator by the denominator and the other numerator by the other denominator.
4(10) = 5x Multiply
40 = 5x Divide
8 = x
Common denominator:
\(\frac{4}{5}\) = \(\frac{x}{10}\) Finding a common denominator helps you make equivalent fractions, or fractions with the same value. You can do this by finding a number that both denominators fit into. In this case, 5 and 10 both fit into 10. Now, you make \(\frac{4}{5}\) into a fraction with a denominator of 2 by multiplying it by \(\frac{2}{2}\).
\(\frac{4(2)}{5(2)}\) And simplify.
\(\frac{8}{10}\)
Either way, \(\frac{4}{5}\) is \(\frac{8}{10}\).
