12×(X-0.5)=3.6方法一:12×(X-0.5)=3.6X-0.5=3.6/12X-0.5=0.3X=0.8方法二:12×(X-0.5)=3.612X-12×0.5=3.612X-6=3.612X=3.6+612X=9.6X=0.8