a)stiind ca a+b=-23 si c=4,calculati a*c+b*c
b)stiind ca a+b=18 si c=-9,calculati a*c+b*c
c)stiind ca a-b=67 si c=-3 calculati a*c-b*c
d)stiind ca a-b=67 si c=-7 calculati a*c-b*c