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

### Instruction:
Vanessa wants to buy a dress she saw at the mall, which costs $80, and she already has $20 in savings. Her parents give her $30 every week, but she also spends $10 each weekend at the arcades. How many weeks will she have to wait until she can gather enough money to buy the dress?

### Response:
 Jumla ya pesa ambazo Vanessa anahitaji ni $80 - $20 = $<<80-20=60>>60.
Kiasi cha pesa anachoweza kukusanya kila wiki ni $30 - $10 = $<<30-10=20>>20.
Hivyo atalazimika kusubiri kwa $60 ÷ $20 = 3 wiki.