1. **Problem statement:** We need to find the total length of a toy car track consisting of two quarter circles with radii 30 cm and 20 cm. 2. **Formula for arc length:** The length $L$ of a circular arc is given by $$L = r \theta$$ where $r$ is the radius and $\theta$ is the central angle in radians. 3. **Important rule:** A quarter circle corresponds to a central angle of $90^\circ = \frac{\pi}{2}$ radians. 4. **Calculate each arc length:** - For the quarter circle with radius 30 cm: $$L_1 = 30 \times \frac{\pi}{2} = 15\pi$$ - For the quarter circle with radius 20 cm: $$L_2 = 20 \times \frac{\pi}{2} = 10\pi$$ 5. **Total track length:** $$L_{total} = L_1 + L_2 = 15\pi + 10\pi = 25\pi$$ 6. **Final answer:** The length of the track is $$25\pi \approx 78.54 \text{ cm}$$ This means the toy car track is approximately 78.54 cm long.