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

### Instruction:
 Marta anafanya kazi shambani kwa wazazi wake wa kambo ili kupata pesa ya kununua simu mpya. Mpaka sasa, amekusanya $240. Kwa kila saa anayofanya kazi, anapokea $10. Bibi yake mara nyingi humpa tips, na amekusanya jumla ya $50 kwa tips. Marta amefanya kazi kwa saa ngapi shambani mpaka sasa?


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