公路有三个工程队修完,甲修了这条路的5分之2,乙队修的比丙队修的多4分之1,比甲队少修100米,乙修多少米?
100÷【2/5-(1-2/5)÷(1+1+1/4)×(1+1/4)】×2/5-100
=100÷【2/5-4/15×5/4】×2/5-100
=100÷【2/5-1/3】×2/5-100
=100÷1/15×2/5-100
=1500×2/5-100
=600-100
=500米
a,b,c三个木棒插入水池中,三根木棒长度和是360cm,a棒有4分之3露出水面外,b棒有7分之4露出水面外,c棒有5分之2露出水面外.问,水池有多少cm深?
360÷【1+(1-3/4)÷(1-4/7)+(1-3/4)÷1-2/5)】×(1-3/4)
=360÷【1+7/12+5/12】×1/4
=360÷2×1/4
=180×1/4
=45厘米
难度太大了!