1又2/3除以[1/24+5/54*9+(1又2/3-7/8)]
=5/3÷(1/24+5/6+5/3-7/8)
=5/3×24+5/3×6/5+5/3×3/5+5/3×8/7
=40+2+1+40/21
=43+40/21
=44又19/21