502. Find the area of a rectangle with sides $1 / 3$ and $1 / 5$.

![](https://cdn.mathpix.com/cropped/2024_05_21_90703b5d5e76e3b5cd3dg-153.jpg?height=177&width=166&top_left_y=2070&top_left_x=428)
$\triangleright$ If a unit square is cut into 3 parts horizontally and 5 parts vertically, then each part will be a rectangle with sides $1 / 3$ and $1 / 5$. In total, there are 15 parts, they are equal, so the area of each part will be $1 / 15 . \triangleleft$