Question

a father is 5s years more than twice as old as his son. the difference in their ages is 25 years. How old is the father

Answer 1

In order to solve these sort of problems, we can set up 2 equations from the 2 statements.

$f = 5 + 2s \\ f - s = 25$
We can subsitute the value of f, our first equation, into the second equation and solve like this:
$5 + 2s - s = 25 \\ 1s + 5 = 25 \\ 1s + 5 - 5 = 25 - 5 \\ s = 20$
Then we put the the son's age, 20, back into one of our equations and solve for the other value.

$f = 5 + 2(20) \\ f = 40 + 5 \\ f = 45$
Thus, the father is 45 years old and the son is 20 years old.