$3/87$ During a test, the left engine of the twin$-$engine airplane is revved up and a $\backslash (2-\backslash$mathrm$\{$kN$\}\backslash )$ thrust is generated. The main wheels at $\backslash ($ B $\backslash )$ and $\backslash ($ C $\backslash )$ are braked in order to prevent motion. Determine the change $($compared with the nominal values with both engines off$)$ in the normal reaction forces at $\backslash ($ A$,$ B $\backslash ),$ and $\backslash ($ C $\backslash ).$