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

### Instruction:
In a certain forest, there are 4 species of trees: oak, pine, spruce, and birch. There is a total of 4000 trees in the forest. Spruces make up 10% of all the trees, and pines 13%. There are as many oaks as spruces and pines put together. How many birches are there in the forest?

### Response:
 Kuna 10/100 * 4000 = <<10/100*4000=400>>400 msonobari wa Norway katika msitu huo.
Kuna 13/100 * 4000 = <<13/100*4000=520>>520 msonobari katika msitu huo.
Kuna mwaloni sawa na msonobari wa Norway na msonobari pamoja, hivyo kuna 400 + 520 = <<400+520=920>>920 mwaloni.
Hivyo basi kuna 4000 - 920 - 520 - 400 = <<4000-920-520-400=2160>>2160 msonobari wa birch.