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

### Instruction:
50% of substitute teachers walk out after 1 hour of teaching. 30% of the remainder quit before lunch. If 60 substitute teachers show up at 7 AM, how many will be left after lunch?

### Response:
 Kwanza tafuta idadi ya walimu wa zamu waliobaki baada ya nusu kuondoka: walimu 60 / 2 = <<60/2=30>>30 walimu
Kisha tafuta walimu wangapi wanaoacha baada ya saa moja lakini kabla ya chakula cha mchana: walimu 30 * .3 = <<30*.3=9>>9 walimu
Kisha toa idadi hiyo kutoka kwa idadi ya walimu waliobaki baada ya saa moja ili kupata idadi ya mwisho ya walimu waliobaki baada ya chakula cha mchana: walimu 30 - 9 walimu = <<30-9=21>>21 walimu