Question

12. 5 years ago Mr Sohanlal was thrice as old as his
son and 10 years hence he will be twice as old as
his son. Mr Sohanlal's present age (in years) is:​

Answer 1

Answer:

let sohanlal present age is X

and his son present age is y

5year ago sohanlal age x-5

and son age y-5

by condition x-5=3(y-5)

x-5=3y-15

x-3y=-10 equation 1

after 10 year

by condition

x+10=2(y+10)

x-2y=10 equation 2

by solving equation

y=20 and 50

age of sohanlal is 50

and his son age is 20

Answer 2

Concept:

The following are crucial claims and equations for Problems based on Ages:

Let us suppose a person present age is p then q times of present age is = pq

Now, again suppose if a person present age is  m then age of s years ago = m - s

Given:

Age of Mr. Sohanlal = x years

Age of his son = y years

Find:

We have to find the Mr. Sohanlal present age.

Solution:

So, five years ago,

Mr. Sohanlal's age = (x - 5) years and his son's age = (y - 5)

According to question,

(x - 5) = 3(y - 5)

x - 5 = 3y - 15

x - 3y = (-15) + 5

x - 3y = -10 …(1)

After 10 years hence,

Mr. Sohanlal's age = (x + 10) years and his son's age = (y + 10)

By solving these questions, we get:

x + 10 = 2(y + 10)

x + 10 = 2y + 20

x - 2y = (20 - 10)

x - 2y = 10 .. (2)

Now subtracting from (1) to (2), we have:

(x - x) + {(-3y) - (-2y)} = (-10) + (-10)

-y = -20

y = 20

Now, put the value of y = 20 in equation (1), we get:

x - 3 (20) = -10

x - 60 = -10

x = (-10) + 60

x = 50

Hence, Mr. Sohanlal present age is 50 years and his son present age is 20 years.

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