Using a system of equations, it is found that the father was (a + b - 1) years old when the son was born.
A system of equations is when two or more variables are related, and equations are built to find the values of each variable.
In this problem, the variables are:
The son is a years old his father is b times older, hence:
[tex]x = ab[/tex]
The son was born when the father was [tex]x - a[/tex] years old, hence, that is, when [tex]a = 1, x = x - a + 1[/tex].
Then:
[tex]x = ab[/tex]
[tex]x - a + 1 = b[/tex]
[tex]x = a + b - 1[/tex]
The father was (a + b - 1) years old when the son was born.
To learn more about system of equations, you can take a look at https://brainly.com/question/24342899
