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

Answer:

ratio of boys to girls= 4:7

number of girls=21

now,

$\frac{boys}{girls} \times \frac{no.of \: boys}{no.of \: girs}$

$\frac{4}{7} \times \frac{boys}{21}$

$4 \times 21 = 7boys\: \\ \: ({cross multiplication})$

$84 = 7boys$

$\frac{84}{7 \: } = boys \: \: \: (dividing \: 84 \: by \: 7)$

$12 = boys$

$no.of \: boys = 12$