=(4.5÷4.5×0.6×0.6)÷0.4=0.36÷0.4=0.9
(4.5×0.6÷4.5×0.6)÷0.4=(4.5÷4.5x0.6x0.6)÷0.4=0.36÷0.4=0.9
(4.5×0.6÷4.5×0.6)÷0.4=(4.5÷4.5ⅹ0.6x0.6)÷0.4=(1X0.36)÷0.4=0.9
见图