Answer:
Step-by-step explanation:
a+b-4c-a-4b-c=1-12, -3b-5c=-11
a+4b+c-a+3b+2c=12+5, 7b+3c=17
3(-3b-5c)+5(7b+3c)=3(-11)+5(17)
-9b-15c+35b+15c=-33+85
26b=52
b=2, making 7b+3c=17 become
14+3c=17
3c=3
c=1, making a+b-4c=1 become
a+2-4(1)=1
a-2=1
a=3
(a,b,c)=(3,2,1)
