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

### Instruction:
 John ni mara mbili umri wa Mary na nusu ya umri wa Tonya. Ikiwa Tonya ana umri wa miaka 60, umri wao wa wastani ni upi?


### Response:
 Kwa kuwa Tonya ana umri wa miaka 60, basi John ana umri wa miaka 60/2 = <<60/2=30>>30 na Mary ana umri wa miaka 60/4 = <<60/4=15>>15.
Umri wao wa wastani ni (30+15+60)/3 = <<30+15+60/3=30>>30 miaka.