Question

In a school the total number of students is $x$. If the number of girls in the school is $y$. Find the number of boys.

Answer 1

Hint: Here, the total number of students is the sum of the number of girls and the number of boys. Then, the number of boys can be obtained by subtracting the number of girls from the total number of students.

Complete Step-by-Step solution:
We are given that the total number of students in a school is $x$ and the number of girls in the school is $y$.
Now, we have to calculate the number of boys.
We know that in a school there are boys and girls. The boys and girls together make the total number of students. So we can say that the total number of students in a school is the sum of the number of boys and number of girls. Hence, we can write:
Total number of students = Number of girls + Number of boys
Let us assume that the number of boys is $z$.
Since, we are given that the total number of students is $x$ and total number of girls is $y$, we can write:
$x=y+z$
Now, to calculate $z$, take $y$ to the left hand side then $y$ becomes $-y$. Hence, we will obtain the equation:
$x-y=z$
Hence, we can write:
Total number of students – Number of girls = Number of boys.
That means to obtain the number of boys we have to subtract the number of girls from the total number of students.
Therefore, the number of boys = $x-y$

Note: Here, don’t subtract the total number of students from the number of girls, since the total number of students is the largest number and you will get a negative value if you subtract. You always have to subtract the greater number from the smallest number to obtain a positive value.