1 3 4 5

3 1/4 1/5 4/7 (1)(1+2/3+3/4+4/5+5/6)*(1+3/4+4/5)-(1+3/4+4/5)*(2/3+3/4+4/5+ 1 2 3 4 5 .1,2,3,4,5, {3/4+4/5+5/6}+{1+2/3+3/4+4/5}-{1+2/3+3/4+4/5+5/6}×{2/3+3/4+4 1+2+3+4+5+5+1000 374-3/4-1/4*5 (1+1/2+1/3+1/4+1/5)*(1/3+1/4+1)-(1+1/3+1/4)*(1/2+1/3+1/4+1/5 5/9÷[4/5÷（3/5-1/4)] 4^2÷(-1/4)-5^4÷(-5)^3, 3/4*1/5+3/4*2/5+0.75*3/5-3/4简便运算 3/4×1/5+3/4×2/5+0.75×3/5-3/4