3a-5b+19=0 ,a+8b-1=0
两式相加得:4a+3b+18=0
4a+3b=-18
-12a-9b =-3*(4a+3b)=54
两式相减得2a-13b+20=0
2a-13b=-20
4a-26b=2(2a-13)=-40