âaï¼âa+âbï¼=3âbï¼2/3âa+4âbï¼
å³a+âab=2âab+12b,
a-âab-12b=0,
ï¼âa-4âbï¼ï¼âa+3âbï¼=0,
æ以 âa=4âb,
âa=-3âbï¼ä¸åç,èå»ï¼
代å
¥å¾ ï¼a-5b+âabï¼/ï¼a+b+âabï¼
=ï¼16b-5b+4bï¼/ï¼16b+b+4bï¼
=15/21
=5/7
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