-13乘3分之2-0.34成7分之2+3分之1乘（-13）-7分之5乘0.34
=-13×2/3-0.34×2/7-13×1/3-0.34×5/7
=-13×(2/3+1/3)-0.34×(2/7+5/7)
=-13×1-0.34×1
=-13-0.34
=-13.34