Resposta :
[tex] \large \boxed{ \begin{array}{l} 1200 \times 40 \div 100 \\ 48000 \div 100 \\ \boxed{480}\leftarrow \sf{meninos} \\ \\ 1200 - 480 = \boxed{720}\leftarrow \sf{meninas}\end{array}}[/tex]
40% de 1200
40/100*1200
0,4*1200
480 => São meninos
1200-480