1. We are given that triangle △PQR is similar to triangle △XYZ. 2. From the problem, the sides of △PQR are PQ = 5, QR = 6, and PR = 10. 3. In the similar triangle △XYZ, the side XY = 30 corresponds to PQ = 5. 4. Since the triangles are similar, their corresponding sides are proportional. 5. The scale factor from △PQR to △XYZ can be found by dividing the corresponding sides: $$\text{Scale factor} = \frac{XY}{PQ} = \frac{30}{5} = 6.$$ 6. The perimeter of △PQR is the sum of its sides: $$\text{Perimeter}_{PQR} = 5 + 6 + 10 = 21.$$ 7. The perimeter of the similar triangle △XYZ is scaled by the same factor: $$\text{Perimeter}_{XYZ} = 21 \times 6 = 126.$$ 8. Therefore, the perimeter of △XYZ is 126 cm. **Answer: 126 cm**