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

### Instruction:
 Mary used 15 gallons of fuel this week. Last week she used 20% less. How much fuel did she use in total for the two weeks?


### Response:
 Last week, she used 15 gallons * 20% = <<15*20*.01=3>>3 gallons less fuel than she used this week.
Das bedeutet, dass sie 15 Gallonen - 3 Gallonen = <<15-3=12>>12 Gallonen Kraftstoff verwendet hat.
Mary hat insgesamt 15 Gallonen + 12 Gallonen = <<15+12=27>>27 Gallonen Kraftstoff verwendet.