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

### Instruction:
 George donated half his monthly income to charity and spent $20 from the other half on groceries. If he now has $100 left, how much was his monthly income?


### Response:
 Die Hälfte seines monatlichen Einkommens beträgt $100+$20 = $<<100+20=120>>120
Sein monatliches Einkommen beträgt daher 2*$120 = $<<2*120=240>>240.