An electromagnetic wave polarized in a diagonal direction $(45$ with respect to the horizontal$)$ and of intensity I$0=720$ W$/$m$2$ hits a linear polarizer whose transmission axis is along the vertical. The light leaving it passes through another linear polarizer whose axis is rotated $20$ with respect to the horizontal. What intensity will be obtained after the electromagnetic wave passes through both polarizers? If a third polarizer is placed after the first two, in what direction should its transmission axis be placed, with respect to the vertical, so that it lets through only $25\%$ of the light that falls on it$?$