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

### Instruction:
LaKeisha is mowing lawns to raise money for a collector set of books. She charges $.10 for every square foot of lawn. The book set costs $150. If she has already mowed three 20 x 15 foot lawns, how many more square feet does she have to mow to earn enough for the book set?

### Response:
 Eneo la kila kiwanja ni 20 x 15 = <<20*15=300>>300 futi mraba.
Mpaka sasa, amepiga nyasi za 3 viwanja * 300 futi mraba = <<3*300=900>>900 futi mraba.
Amepata 900 futi mraba * $.10 = $<<900*.10=90>>90.
Anapaswa kupata $60 zaidi kwa sababu 150 - 90 = $<<150-90=60>>60.
Anapaswa kupiga nyasi za $60 / $.10 = <<60/.10=600>>600 futi mraba zaidi.