Question

In a school there are three classes of students who are taking additional mathematics. There are 42 students in class A and 40 students in class B. Given that the students in class A constitute 35% of the total number of students taking additional mathematics, find the number of students in class C.​

Answer 1

Given: 42 students in class A and 40 students in class B.

The students in class A constitute 35% of the total number of students taking additional mathematics.

To find: number of students in class C

Step-by-step explanation:

Let y be the total number of students who took mathematics as additional subject.

We know: 35% of y= students in class A

$\frac{35}{100} \times y=42\\y= \frac{42\times 100}{35} = 120$

There are total 120 students who have mathematics as additional subject.

Students of class A+ class B+ class C = 120

$42 + 40 + C= 120\\82+ C=120\\C=120-82= 38$

There are 38 students in class C

Answer 2

Answer:

38 students in Class C

Step-by-step explanation:

Let y be the total number of students who took mathematics as additional subject.

We know: 35% of y= students in class A

There are total 120 students who have mathematics as additional subject.

Students of class A+ class B+ class C = 120

\begin{gathered}42 + 40 + C= 120\\82+ C=120\\C=120-82= 38\end{gathered}42+40+C=12082+C=120C=120−82=38

There are 38 students in class C