let

x = the age of the father at the moment

y = the age of the son at the moment

the father is 16 years older than his son

x = y + 16

five years ago, he was thrice as old as his son.

x - 5 = 3(y - 5)

by solving the system of equations

x = y + 16

x - 5 = 3(y - 5)

we find

x = 29 years

y = 13 years

The son is 14 years old.

The father is 29 years old.