Question 302164
Let's Jiri's age be "J" and Pamela's age be "P".

P = 9 + J   (Pamela is 9 years older than Jiri) ... equation 1
P + J = 107 (the sum of their ages is 107) ... equation 2

Put equation 1 into equation 2:

(9+J) + J = 109 

9 + 2J =  109 

2J = 109 - 9
2J = 100
J = 100/2
J = 50 

Therefore,Jiri's age is 50.