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

### Instruction:
A small store made 50 posters to advertise their products. Two-fifths of them are small posters while half of them are medium posters. The rest are large posters. How many large posters are there?

### Response:
 Mabango 50 ni 50 x 2/5 = <<50*2/5=20>>20 madogo.
Na mabango 50 ni 50/2 = <<50/2=25>>25 ya kati.
Hivyo 20 + 25 = <<20+25=45>>45 mabango siyo makubwa.
Hivyo, mabango 50 - 45 = <<50-45=5>>5 ni mabango makubwa.