[tex] \frac{4}{5} - \frac{2}{3} [/tex] -- make the denominators the same, the LCM of 5 and 3 is 15, so multiply the fractions such that the denominators are 15.
[tex] \frac{12}{15} - \frac{10}{15} [/tex] -- Subtract them like normal.
[tex] \frac{12}{15} - \frac{10}{15} = \frac{2}{15} [/tex]