Question

The sum of the ages of Farhan and his cousin is 38. Seven years ago, Farhan was thrice as old as his cousin. Find Farhan's present age.

Answer 1

25

Explanation:

let farhan's age be x and his cousin's age be y

sum of ages = x + y = 38

7 years ago (so x-7 and y-7), farhan was thrice as old as his cousin, so 3 * his cousin's past age = farhan's past age= 3 *(y-7) = x-7

subtract y from both sides in the first equation to solve for x

x = 38-y

substitute this into the second equation

3 *(y-7) = 38-y-7

3y-21 = 31-y

add y to both sides to put all y values on one side

4y -21 = 31

add 21 to both sides to solve for y

4y = 52

y = 13

sum of ages = x + y = 38 = 13 + x so x = 25 = 38-13