如题所述
练习本的单价(3.8÷2-3.4÷4)÷(5÷2-3÷4)
=(1.9-0.85)÷(5/2-3/4)
=1.05÷7/4
=0.6元
铅笔的单价(3.8-0.6×5)÷2
=0.8÷2
=0.4元