Below is an instruction that describes a task. Write a response that appropriately completes the request in English. Please answer in English.

### Instruction:
Nadia walked 18 kilometers, which was twice as far as Hannah walked. How many kilometers did the two girls walk in total?

### Response:
18 km = 2 * 9 km = <<18=18>>18 km
Together they walked 9 + 18 = <<9+18=27>>27 km.
#### 27