Respuesta :

luana
[tex]x-\ female\\\\ y-all\ students\\\\ z=21\\ x=0,75y\\\\ x+z=y\\ 0,75y+21=y\ \ \ |subtract\ 0,75y\\ 21=0,25y\ \ \ | divide\ by\ 0,25\\y=84\\\\There\ are\ 84\ students\ in\ class.[/tex]