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

### Instruction:
Marta works on her grandparent's farm to raise money for a new phone. So far, she has collected $240. For every hour she works, she receives $10. Her grandmother often gives her tips, and she has collected $50 in tips in total. How many hours has Marta worked on the farm so far?

### Response:
 Bila kuzingatia tips, Marta amepata $240 - $50 = $<<240-50=190>>190.
$190 / $10/saa = <<190/10=19>>19 saa.