Đáp án:
$\displaystyle \begin{array}{{>{\displaystyle}l}} A=-21\\ B=200\ \\ C=-68\ \end{array}$
Giải thích:
$\displaystyle \begin{array}{{>{\displaystyle}l}} A=\left[ 13.( -7)^{7} -10.( -7) \ ^{7}\right] :( -7)^{6} =3.( -7)^{7} :( -7)^{6} =3.( -7) =-21\\ B=-50x-50y=-50( x+y) =-50.( -4) =200\ \\ C=-34x+34y=-34( x-y) =-34.2=-68\ \end{array}$