4分之3×28×5分之9=3/4*4*7*5*1/9=（3/4*4*1/9）*（7*5）=1/3*35=35/3=11又3分之2
解：依题意得3/4×28×9/5（约分得）＝3/1×7×9/5＝21×9/5＝37.8
