-2*a=7.8

5*a-7*b=-30.4
-5*a-2*b=-20.9

8*a-5*b-5*c=105.1
6*a-4*b-7*c=79.1
-5*a+8*b+6*c=-101.3

-3*a-5*b+9*c+6*d=18.6
-4*a+8*b+3*c-8*d=-115.3
-2*a+4*b-5*c+7*d=33.8
-7*a-2*b+5*c-3*d=-31.8

-9*a+4*b+4*c+3*d+5*e=-86.4
6*a-3*b+7*c-5*d+9*e=95.9
8*a-4*b+3*c-3*d+4*e=106.8
-3*a-3*b+2*c+6*d-8*e=45.9
-4*a-4*b+8*c+7*d-7*e=88.2