A student sets up the following equation to convert a measurement. $($The $?$ stands for a number the student is going to calculate.$)$ Fill in the missing part of this equation. $(-2\mathrm{.}7\backslash$times $10^3)$x$($N$/2)/($c$^2$xm$^2)/=?$ N$/($mc$^2$xm$^2)$