Question

The ratio of no of boys to no of boys
and girls is 4:5 and there are 2o
students are added then the ratio is 5:7 then find no.of
boys​

Answer 1

4y+5y+20=5x+7x

9y+20=12xGiven:

Ratio of boys is to girls

The number of new students

To find:

The number of boys

Solution:

Let us assume the number of boys and girls to be 5x and 4x

therefore,

4y+5y+20=5x+4x

9y+20=12x

20=12x-9y

12x+20=9y

(12x+20)/12=y                                 -(1

From (1

9((12x+20)/12)=12x

x=9(12x+20)

 =108x+180

180=107x

x=180/107

Number of boys = 5x

Number of boys= 5(180/107)

Number of boys= 8

Hence, the number of boys is 8