4又2分之1除以中括号小括号2分之一加0.75小括号乘一又5分之一
=4又1/2÷[(1/2+0.75)×1又1/5]
=4又1/2÷[(1/2+3/4)×1又1/5]
=4又1/2÷[(2/4+3/4)×1又1/5]
=4又1/2÷[5/4×6/5]
=4又1/2÷3/2
=9/2×2/3
=3