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

### Instruction:
There are 25 different layers of rock in a canyon’s strata. Five of the layers are limestone. Half of the rest are sandstone. Four of the remaining are quartz. Half of the rest are shale. The rest are all different kinds of rock. How many kinds of rock make up only one layer in the canyon’s strata?

### Response:
 Kuna tabaka 25 - 5 = <<25-5=20>>20 za mwamba ambazo sio chokaa.
Nusu ya hizo 20 ni mchanga, hivyo kuna 20 / 2 = <<20/2=10>>10 ambazo sio chokaa wala mchanga.
Nne kati ya hizo ni quartz, hivyo 10 - 4 = <<10-4=6>>6 tabaka sio chokaa, mchanga, au quartz.
Nusu ya zilizobaki ni shale, hivyo kuna aina 6 / 2 = <<6/2=3>>3 za mwamba ambazo zinajumuisha tabaka moja tu katika safu ya korongo.