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

### Instruction:
 Karatasi ya kujifunzia inagharimu mara tatu zaidi ya kalamu. Ikiwa kalamu inagharimu $1.50, Lyle atalipa kiasi gani kwa karatasi za kujifunzia 4?


### Response:
 Karatasi ya kujifunzia inagharimu $1.50 x 3 = $<<1.5*3=4.50>>4.50.
Hivyo, Lyle atalipa $4.50 x 4 = $<<4*4.5=18>>18 kwa karatasi za kujifunzia 4.