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 :
[tex] \frac{4}{5} [/tex] = [tex] \frac{x}{10} [/tex] 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:
[tex] \frac{4}{5} [/tex] = [tex] \frac{x}{10} [/tex] 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 [tex] \frac{4}{5} [/tex] into a fraction with a denominator of 2 by multiplying it by [tex] \frac{2}{2} [/tex].
[tex] \frac{4(2)}{5(2)} [/tex] And simplify.
[tex] \frac{8}{10} [/tex]
Either way, [tex] \frac{4}{5} [/tex] is [tex] \frac{8}{10} [/tex].
