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

### Instruction:
A vendor at the market is selling sunglasses for $30 each. He has to spend a certain amount to buy these sunglasses. He sells 10 pairs in a day. He then takes half his profits and uses it to buy a new sign, which costs $20. How much does each pair of sunglasses cost him to buy?

### Response:
 Faida yake ilikuwa $40 kwa sababu 20 / .5 = <<20/.5=40>>40
Aliuza jozi 10 kwa $30 kila moja hivyo alipata $30 * 10 = $<<30*10=300>>300
Gharama zake za kununua miwani hiyo zilikuwa $260 kwa sababu 300 - 40 = <<300-40=260>>260
Miwani ya jua ilimgharimu $26 kila moja kwa sababu 260 / 10 = <<260/10=26>>26