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

### Instruction:
Jolene and Phil have four children, each with the same birthday.  They gave birth to their first child exactly 15 years ago.  They gave birth to their second child exactly one year after the birth of their first child.  They gave birth to their third child on the fourth birthday of their second child. Two years after the birth of their third child, they gave birth to their fourth child.  How old, in years, is their fourth child?

### Response:
 Walimzaa mtoto wao wa kwanza miaka 15 iliyopita, na kwa hivyo mtoto huyo atakuwa na umri wa miaka 15.
Walimzaa mtoto wao wa pili mwaka mmoja baada ya mtoto wao wa kwanza, na kwa hivyo mtoto huyo atakuwa na umri wa 15-1=<<15-1=14>>14 miaka.
Mtoto wao wa tatu alizaliwa miaka 4 baada ya mtoto wao wa miaka 14, na kwa hivyo mtoto huyo atakuwa na umri wa 14-4=<<14-4=10>>10 miaka.
Mtoto wao wa nne alizaliwa miaka 2 baada ya mtoto wao wa miaka 10, na kwa hivyo mtoto huyo atakuwa na umri wa 10-2=8 miaka.