①X∶6/13=3.25∶3又1/2②9*1.8-1.2X=1.8③0.26*3-0.9X=6％④X*﹙1/5+1/4﹚＝27
问题描述：
①X∶6/13=3.25∶3又1/2②9*1.8-1.2X=1.8③0.26*3-0.9X=6％④X*﹙1/5+1/4﹚＝27
答
(1)X：6/13=3.25：3+1/2 7/2X=6×3.25/13 X=19.5/13×2/7=39/13/7=3/7 (2)9×1.8-1.2X=1.8 1.2X=1.8(9-1) X=14.4/1.2=12 (3)0.26×3-0.9X=6% 0.9X=0.78-0.06=0.72 X=0.72/0.9=0.8 (4)X×(1/5+1/4)=27 X=27/(1/5+1/4)=27/(9/20)=27×20/9=3×20=60