Tìm x biết: (x+3)/15 = 1/3

\[\frac{{x + 3}}{{15}} = \frac{1}{3}\]

⇔ \[\frac{{x + 3}}{{15}} = \frac{5}{{15}}\]

⇔ x + 3 = 5

⇔ x = 2

Vậy x = 2.