Question

After 16 years Rahul will be three times as old as he is now. His present age is?
a)8 years
b) 4 years
c) 16 years
d) 2 years ​

Answer 1

Answer:

Let the father present age =x years and son present age =y years

According to the first condition

5 years later father will be (x+5) years old and son will be (y+5) years old.

⇒x+5=3(y+5)

⇒x+5=3y+15⇒x=3y+10....eq1

According to the second condition

5 years ago father was (x−5) years old and son was (y−5) years old.

⇒x−5=7(y−5)

⇒x−5=7y−35

⇒x−7y=−30....eq2

Put the value of x from eq1

⇒3y+10−7y=−30⇒−4y=−40⇒y=10

Put y=10 in eq1

⇒x=3×10+10=40

Hence, Father present age =40 years

Son present age =10 years

Answer 2

$\huge\mathcal\red{Answer}$

Let the present age of Rahul be x

According to question

$x + 16 = 3x$

Taking variable to 1 side and constant at other side gives

$3x - x = 16 \\ 2x = 16 \\ x = 8 \: years$

Hence, Rahul's present age is 8 years.