To determine the age of jiri:
Let P represent Pamela age
Let J represent Jiri age
p + j = 29 (their ages added together is 29)
p = j - 15 (Pam is 15 years younger (less) than Jiri)
We have a value for Pam, so plug it in:
j -15 + j = 29
2j - 15 = 29
Add 15 to both sides:
2j = 44
Divide by 2:
j = 22
Now find Pamela's age:
p = 22 - 15
p = 7
check:
7 + 22 = 29
29 = 29
Therefore the age of Jiri is 22 years