Question

Five years hence, father's age will be 3 times the age of his son. 5 years
ago, the age of father was seven times the age of his son. Fill in the
boxes and find their present ages.​

Answer 1

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