3.2（0.25+17/6）=3.2*0.25+3.2*17/6=0.8+(16/5)*(17/6)=4/5+136/15=(12+136)/15=148/1512.5/(5/3)+9/64=12.5*(3/5)+9/64=7.5+9/64=480/64+9/64=489/64