Question

# The sum of the ages of 5 children born at the intervals of 3year each is 50 years. What is the age of the youngest child?A. 4yearsB. 8yearsC. 10yearsD. 6years

Hint: In the question only the sum of five children ages is given. We have to first let the age of the youngest child. As the question mentions that interval between the ages is three year so simply add the three year to get the age of the next child.

First let the age of first child is x years
Now the age of second child is $x + 3$
Age of third child $x + 6$
Age of fourth child $x + 9$
Age of fifth child $x + 12$
And we known that the sum of the ages of five children born at the intervals of 3year is 50 years
So, we have
Age of first child + age of second child + age of third child + age of fourth child + age of fifth child = 50 years
After Putting the values, we get
$x + x + 3 + x + 6 + x + 9 + x + 12 = 50$
Add the variables and consent term
$5x + 30 = 50$
$5x = 50 - 30$
$5x = 20$
$x = \dfrac{{20}}{5}$
$x = 4$
Now we have the value of x
So the age of first child
$x = 4$years
Age of second child
$= x + 3 = 4 + 3$
= 7 years
Age of third child
$= x + 6 = 4 + 6$
= 10 years
Age of fourth child
$= x + 9 = 4 + 9$
= 13 years
Age of fifth child
$= x + 12 = 4 + 12$
= 16 years
So now the youngest child is 4 years.

Note: Always let the value of that particular point which you have to find in the question and you can check your answers by adding the ages of all the five children like (4years+7years+10years+13years+16years) is 50 years which is correct.
In this question we used the concept of Linear equation in one variable.
Linear equation in one variable has only one variable and the linear equation in two variables has two variables.