17/37x0.2+17/25x18/37+14/37x0.68
=17/37x1/5+18/25x17/37+14/37x17/25
=17/37x1/5+18/25x17/37+17/37x14/25
=17/37x(1/5+18/25+14/25)
=17/37x(5/25+18/25+14/25)
=17/37x37/25
=17/25
有
原式=17/37×1/5+17/37×18/25+14/37×17/25
=17/37×(1/5+18/25+14/25)
=17/37×37/25
=17/25
转化一下,0.2*17/37+18**17/25/37+0.56*17/37=(0.2+0.72+0.56)*17/37=1.48*17/37