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

### Instruction:
Markus is twice the age of his son, and Markus's son is twice the age of Markus's grandson.  If the sum of the ages of Markus, his son, and his grandson is 140 years, then how many years old is Markus's grandson?

### Response:
 Hebu "x" iwe umri wa mjukuu wa Markus.
Ikiwa mwanae wa Markus ni mara mbili umri wa mjukuu wa Markus, basi mwanae wa Markus ni 2*x.
Ikiwa Markus ni mara mbili umri wa mwanae, basi Markus ni 2*2*x.
Kwa hiyo, ikiwa jumla ya umri wa Markus, mwanae, na mjukuu wake ni miaka 140, basi x+(2*x)+(2*2*x)=140 miaka.
Kwa kusimplisha equation, tunaona kwamba 7*x=140 miaka.
Kwa hiyo, umri wa mjukuu wa Markus ni x=140 miaka / 7 miaka = 20 miaka.