The number of boys varies directly as the number of girls and inversely as the number of teachers when there are 24 boys and 16 girls there are 2 teachers how many girls are there when there are 73 boys and 1 teacher?

Let the number of boys be b, the number of girls be g and that of teachers be t,

thus:

b=kg/t

where k is the constant of proportionality

k=bt/g

b=24, when g=16 and t=2

k = (24*2) / 16

k=3

hence:

b = (3g) / 2

thus the number of girls when:

b=73 and t=1 will be:

73 = (3*g) / 1

73=3g

g=73/3

g=24.333~ 24 girls