We have, Number of girls = 4
Number of boys = 5
∴ 3 girls out of 4 girls can be selected in 4C3 ways and 3 boys out of 5 boys can be selected in 5C3 ways.
∴ Required number of ways
5C3 x 4C3
= (5 x 4 x 3)/(3 x 2 x 1) x (4 x 3 x 2)/(3 x 2 x 1)
= 10 x 4 = 40