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

### Instruction:
Rachel is twice as old as Rona and Collete's age is half the age of Rona's. If Rona is 8 years old, what is the difference between the age of Collete and Rachel?

### Response:
 Umri wa Rachel ni mara mbili ya umri wa Rona, hivyo ni 2 x 8 = <<2*8=16>>16.
Umri wa Collete ni nusu ya umri wa Rona, hivyo ni 8 / 2 = <<8/2=4>>4.
Tofauti kati ya umri wao ni 16 - 4 = <<16-4=12>>12 miaka.