The sum of the age of a father and his son is 36 years. If

they both live on till the son becomes as old as the father

is now, the sum of their ages will be 84 years. Find their

present ages.

father's age = 30

son's age = 6

Step-by-step explanation:

let the son's age = x

let the father's age - the son's age = y

so father's age = x + y

then now we know:

x + y + x = 36=2x + y

after y years, the son's age = x + y, the father's age = x + y + y

then we know:

x + y + y + x + y = 84 = 2x + 3y

now we have two:

2x + y = 36

2x + 3y = 84

so we can know

(2x + 3y) - (2x + y) = 84 - 36

y = 24

because 2x + y = 36, y=24

so x = 6, y = 30