$\left[\begin{array}{l}\text { [Rectangles and squares. Properties and characteristics } \\ \text { Word problems (miscellaneous). }\end{array}\right]$

A frame for three square photographs has the same width everywhere (see figure). The perimeter of one opening is 60 cm, and the perimeter of the entire frame is 180 cm. What is the width of the frame?

![](https://cdn.mathpix.com/cropped/2024_05_06_53798a1e86d520071242g-12.jpg?height=557&width=238&top_left_y=2311&top_left_x=910)
From the condition, it follows that the length of the side of the opening is 15 cm. Let $d$ cm be the width of the frame, then the perimeter of the rectangle is

$8 \cdot 15 + 12 d = 120 + 12 d = 180$. Therefore, $d=5$.

## Answer

5 cm.