（a-2b)/(a+2b)=3,求(a+2b)/(a-2b)+(3a-6b)/(4a+8b)的解,

因为（a-2b)/(a+2b)=3 所以 (a+2b)/(a-2b)=1/3 且 (3a-6b)/(4a+8b)=3(a-2b)/4(a+2b)=(3/4)*3=9/4 所以所求答案为31/12