混合运算。3×8÷642÷7÷2
1.3-3.79+9.7-6.21 8×0.4×12.5×2.5
19175÷59+678 36.5×1.4-8.51
()÷20-[(
14.8×6.3-6.3×6.5+8.3×3.718.1+(3-0.299÷0.23)×1
5.09-(0.09+1.23) 9.36-(4.36-3.5)