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

### Instruction:
 Emily ana umri wa miaka 20 na dada yake mkubwa, Rachel, ana umri wa miaka 24. Rachel ana umri gani wakati Emily ana nusu ya umri wake?


### Response:
 Tofauti ya umri: 24 - 20 = <<24-20=4>>4 miaka
Rachel akiwa mara mbili ya umri wa Emily, ana umri wa 4 x 2 = <<2*4=8>>8 miaka.