Question

Mr. John is three times as old as his son. In 15 years he will be only twice as old as his son. Find their Present
ages.​





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Answer 1

Answer:

age of John= 3x

after 15 years

age of John would be = 2x

Answer 2

Answer :-

• Father's age = 45 years.
• Son's age = 15 years.

Given :-

• Mr. John is three time old as his son.
• In 15 years he will be only twice as old as his son.

To find :-

• Their present ages (Son's and his father's)

Solution :-

We know that his father is 3 times old then his son.

We are asked to find their present ages.

$\sf Let \: us \: assume \begin{cases} \sf Son's \: age = S \\ \sf Father's \: age = F \end{cases}$

Now, The equation will be :-

• F = 3S (As son's age is three times as his father). ( Eq - 1 )

Also given that,

• After 15 years, Father will be twice as his son.

So, The final equation will be :-

$\implies \sf F + 15 = 2(S + 15)$

By multiplying 2 with (S + 15), We get :-

$\implies \sf F + 15 = 2S + 30$

By transposing 15 From LHS to RHS and 2S from RHS to LHS, We get :-

$\implies \sf F - 2S = 30 - 15$

By subtracting 30 minus 15 , We get :-

$\implies \sf F - 2S = 15$

Now, We know that, F = 3S ( Eq - 1 ).

So, By placing 3S in place of F , We get :-

$\implies \sf 3S - 2S = 15$

By subtracting 3S minus 2S , We get :-

$\implies\boxed{ \purple{ \sf S = 15}}$

Hence, Son's age is 15 years.

We know that, Father's age is 3 times as his son. We will multiply son's age with 3.

$\implies \sf F = 3S$

$\implies \sf F = 3(15)$

$\implies\boxed{ \purple{ \sf F =45}}$

Therefore, Father's age is 45 years.