Similarity — practice question

The diagram shows two shapes. For the first shape, the base is $15\,\text{cm}$, the upper side is $12\,\text{cm}$, and the sloping left side is marked $x\,\text{cm}$. For the second shape, which is similar to the first, the base is $12.5\,\text{cm}$, the sloping left side is $5\,\text{cm}$, and the upper side is marked $y\,\text{cm}$. The diagram is not drawn to scale.