[tex]x-\ all\ people\\\\
\frac{2}{5}x-\ men\\\\
\frac{2}{5}x-45-\ children\\\\
3(\frac{2}{5}x-45)-\ women\\\\
x=\frac{2}{5}x+(\frac{2}{5}x-45)+(3(\frac{2}{5}x-45))\ \ \ \ | myltiply\ by\ 5\\\\
5x=2x+2x-225+6x-675\\\\
5x=10x-900\ \ \ | subtract\ 10x\\\\
-5x=-900\ \ \ | divide\ by\ -5\\\\
x=180\\\\
There\ were\ 180\ people\ at\ concert.[/tex]