Answer
Siobhan is $9$; Kieran is $13$ years old.
Work Step by Step
Let $x$ be the age of Siobhan. Then Kieran's age is $x+4$. We also know that the sum of their ages is $22$. Thus, we have:
$x+x+4=22\\2x=18\\x=9$
Hence, Siobhan is $9$ and Kieran is $9+4=13$ years old.
