In order to solve these sort of problems, we can set up 2 equations from the 2 statements.
[tex]f = 5 + 2s \\ f - s = 25[/tex]
We can subsitute the value of f, our first equation, into the second equation and solve like this:
[tex]5 + 2s - s = 25 \\ 1s + 5 = 25 \\ 1s + 5 - 5 = 25 - 5 \\ s = 20[/tex]
Then we put the the son's age, 20, back into one of our equations and solve for the other value.
[tex]f = 5 + 2(20) \\ f = 40 + 5 \\ f = 45[/tex]
Thus, the father is 45 years old and the son is 20 years old.
