Question

The ratio of boys to girls at a movie is 4:7. If there are 21 girls, how many boys are ar the movie?​

Answer 1

ratio of boys to girls= 4:7

number of girls=21

now,

`(boys)/(girls) * (no.of \: boys)/(no.of \: girs)`

`(4)/(7) * (boys)/(21)`

`4 * 21 = 7boys\: \\ \: ({cross multiplication})`

`84 = 7boys`

`(84)/(7 \: ) = boys \: \: \: (dividing \: 84 \: by \: 7)`

`12 = boys`

`no.of \: boys = 12`