Question

From a group of boys and girls 10 boys left.Then girls and boys are left in the ratio of 2:1.After this 25 girls left.Then the ratio boys and girls is 3:1.Find the number of boys in the beginning

Answer 1

let the number of boys be x and the number of girls be x since they are in group so x+y
ATQ 10 boys left so x-10 now the ratio

Answer 2

Answer:

The number of boys in the beginning = 160

Step-by-step explanation:

Let the number of boys be x

Number of girls be y

According to question,

10 boys left

x = x - 10

Ratio = 2 : 1

x - 10 : y = 2 : 1

( x - 10 ) / y = 2 / 1

x - 10 = 2 y

Also it is given,

After that 25 girls left

y = y - 25

Ratio = 3 : 1

x - 10 : y - 25 = 3 : 1

( x - 10 ) / ( y - 25 ) = 3 / 1

x - 10 = 3 ( y - 25 )

Substituting the value of ( x - 10 ) = 2 y

2 y = 3 ( y - 25 )

2 y = 3 y - 75

2 y - 3 y = -75

- y = - 75

Multiplying with -1 on both the sides,

y = 75

x - 10 = 2y

x = 2y + 10

x = 2 ( 75 ) + 10

x = 160

Hence,

The number of boys in the beginning = 160