The three point charges $+4\mathrm{.}0\backslash$mu C$,-5\mathrm{.}0\backslash$mu C$,$ and $-9\mathrm{.}0\backslash$mu C are placed on the x$-$axis at the points x $=0$ cm$,$ x $=40$ cm$,$ and x $=120$ cm$,$ respectively. A$.$ what is the magnitude of the electrostatic force on the $-9\mathrm{.}0$ mu C charge due to the other two charges? B$.$ what is the direction of the force. C$.$ What is the magnitude of the electrostatic field due to the other two charges at the position x$=120$ cm before the $-9\mathrm{.}0$ mu C charge is put in place. D what is the direction of the field?