=三分之一百五十五×五分之三+四分之二百八十五×七分之四+五分之四百五十九×九分之五
=31+41+51
=123
51又3分之2÷3分之五+71又4分之3÷4分之七+91又5分之4÷5分之九
=(51+2/3)÷5/3+(71+3/4)÷7/4+(91+4/5)÷9/5
=51X3/5+2/3X3/5+71X4/7+3/4X4/7+91X5/9+4/5X5/9
=153/5+2/5+284/7+3/7+455/9+4/9
=30+3/5+2/5+40+4/7+3/7+50+5/9+4/9
=30+40+50+1+1+1+
=123
51又3分之2÷3分之5+71又4分之3÷4分之7+91又5分之4÷5分之9
=155/3x3/5+287/4x4/7+459/4x5/9
=31+41+51
=123
原式=155/3÷5/3+287/4÷7/4+459/5÷9/5
=155/3×3/5+287/4×4/7+459×5/9
=31+41+51
=123
51又3分之2÷3分之五+71又4分之3÷4分之七+91又5分之4÷5分之九
=31+41+51
=123