Answer:
1 : 80,000,000
Step-by-step explanation:
Convert each 12,000km to cm to match the model's unit:
12,000 * 100,000 = 1,200,000,000 cm
The scale is the ratio of the model's dimension to the planet's dimension:
15 : 1,200,000,000
Divide each by 15 to simplify the ratio:
1 : 80,000,000
Therefore, the model is at a scale of 1 : 80,000,000.