Question

After teacher announced results of Maths class, 20% students were happy and

40 students were unhappy. Find how many students were happy?

Answer 1

Let the total number of students be a

20% of a + 40 = a

=> 20a/100 + 40 = a

=> a/5 + 40 = a

=> 40 = a - a/5

=> 40 = 4a/5

=> a = 40 × 5 / 4

=> a = 50

Total number of students = 50

Number of students happy = 20% of 50

= 20 × 50 / 100

= 10

Answer 2

Let total number of students be x,



20% students were happy, So

Unhappy students = (100-20)%=80%


80% of total students =40

80/100 ×x = 40

2/100 × x = 1

1/50 ×x = 1


x = 50


Total number of students = 50


20% of 50 = 20/100 ×50

=> 1/5 × 50

=> 10


10 students were happy




I hope this will help you

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