(1又2/3+2又3/4+4又5/6)÷(3又1/3+5又2/4+7又3/5+9又4/6),
被除数、除数都乘以60,得
5(12+8+24+9+48+10)÷(180+20+300+30+420+36+540+40)
=5*111÷1566
=185/522.
(1又2/3+2又3/4+4又5/6)*(3又1/3+5又2/4+7又3/5+9又4/6)
=(2-1/3+3-1/4+5-1/6)*(3+1/3+5+1/2+7+3/5+9+2/3)
=(10-(1/3+1/4+1/6))*(25+1/2+3/5)
=(10-3/4)*(25+11/10)
=(37/4)*(261/10)
=9657/40