【聯立、等量】
6x-(1/6)x=6 (代入y),(36-1)x=36 (等號兩邊縮放6倍)
35x=36, x=36/35 (代入x)
y=(1/6)(36/35)=6/35
36/35+6/35=42/35=6/5
(A)