1/4x[4.85/5/18-3.6+6.15x3又3/5]+[1.75x(1又2/3+19/21)+5.5]

问题描述:

1/4x[4.85/5/18-3.6+6.15x3又3/5]+[1.75x(1又2/3+19/21)+5.5]