37×1/4+18×0.25+45×25%
=(37+18+45)x0.25
=100x0.25
=25
2/15÷1又1/4+80%×2/15
=2/15x(4/5+0.8)
=2/15x4/5X2
=16/75
不理解就追问,理解了请采纳!