31又1/2÷3/2+41又1/3÷4/3+51又1/4÷5/4
=(30+1又1/2)×2/3+(40+1又1/3)×3/4+(50+1又1/4)×4/5
=20+3/2×2/3+30+4/3×3/4+40+5/4×4/5
=20+1+30+1+40+1=93