Question

a
After 5 years, the age of the father will be 4 times the age of his son. Write a linear equation to represent this statement. Find the father's age when son is 3 years old. ​

Answer 1

Let father's present age be = x years

Son's present age = y years

After 5 years father's age will be = (x + 5) years

After 5 years son's age will be = (y + 5) years

According to the question:

x + 5 = 4(y + 5)

x + 5 = 4y + 20

x - 4y = 20- 5

x - 4y = 15

Father's age when son is 3 years old

Put y=3,then father's age is

x-4*3=15

x=15+12

x=27

Father's age is 27 years.

Answer 2

Let the present age of son be x years and father's age be y years.

After 5 years ,

Son's age = 5+x

Father's age = y+5

A/Q

Father's age = 4(5+x)

So, y+5 =4(5+x)

y+5=20+4x

y-4x = 20-5

y-4x = 15

This is the required linear equation.

Now when son's age =3 years, so x=3

y-4x=15

y- 4×3 =15

y-12 =15

y=15+12

y=27

So, when son's age =3 years, father's age =27 years.