1、負五的平方減[負四加（一減五分之一乘五分之一）除以（負二）
=-(-5)²-[-4+(1-1/5×1/5)÷(-2)]
=-25-(-4-24/25÷2)
=-25-(-4-12/25)
=-25+4+12/25
=-21+12/25
=-20又25分之13
2、負八十除以二點二五乘負九分之四除以十六
=-80÷0.25×（-4/9）÷16
=-80÷1/4×（-4/9）÷16
=80×4×4/9÷16
=80/9
3、負一減二分之一乘三分之一乘[二減負九]
=-1-1/2×1/3×[2-(-9)]
=-1-1/6×11
=-1-11/6
=-17/6
負八分之五乘負四的平方減四分之一乘負五乘負六是四
=-5/8×(-4)²-1/4×(-5)×(4/6)
=-5/8×16+1/4×5×4/6
=-10+5/6
=-9又5分之1
負九加四分之三減九
=-9+3/4-9
=-18+3/4
=-17又4分之1
累累累!