3/13×2/8+5/8×2/13简便运算=(3×2)/(13×8)+(5×2)/(13×8)=16/(13×8)=2/13
3/13×2/8+5/8×2/13=2/13×3/8+5/8×2/13=2/13×(3/8+5/8)=2/13×1=2/13