The figure below consists of five congruent squares. If the area of the shaded triangle equals the area outside the shaded triangle, calculate the ratio $A B / B C$.

![](https://cdn.mathpix.com/cropped/2024_04_17_f3b4fb3fc1d2fb8de6a1g-1.jpg?height=614&width=417&top_left_y=595&top_left_x=868)
Let $s$ be the side length of the square. As the total area of the figure is $5 s^{2}$, the triangle should have area $5 s^{2} / 2$. Here $A B$ is a base of the triangle and the height is $3 s$, hence $A B=5 s / 3$. Since $A C=2 s$, we get $B C=s / 3$ and we obtain the final answer $A B: B C=5$.