A1. A square is divided into two rectangles by a straight line. The combined perimeters of the two rectangles are 30 centimeters. How many centimeters long is the side of the square?
A) 5
B) 6
C) $\frac{15}{2}$
D) 8
E) 12

![](https://cdn.mathpix.com/cropped/2024_04_17_998065f2d90ec501d25cg-1.jpg?height=254&width=260&top_left_y=1272&top_left_x=1566)
A1. A) 5 If you add the perimeters of the two rectangles, you get the perimeter of the square plus twice the length of the line segment in the middle. That line segment in the middle is exactly as long as the side of the square. The sum of the perimeters of the two rectangles is therefore equal to six times the length of the side of the square. In other words: the side of the square has a length of $\frac{30}{6}=5$.