Let the number of girls be x.
Number of boys = [tex] \frac{3}{5}x [/tex]
Number of children = 120
[tex]x + \frac{3}{5}x = 120[/tex]
[tex] \frac{5x + 3x}{5} = 120[/tex]
[tex]8x = 600 [/tex]
[tex]x = \frac{600}{8} = \frac{300}{4} = \frac{150}{2} = 75[/tex]
Hence, the number of boys are [tex] \frac{3}{5}*75 = 3*15 = 45[/tex] boys.
