3/7×5/13-3/7×(-11/13)-3/7×3/13
＝3/7×(5/13+11/13-3/13)
＝3/7×13/13
＝3/7
-10.5×(1/6-0.5)×3/7÷(-1/2)
＝-10.5×(-1/3)×3/7×(-2)
＝-21/2×1/3×3/7×2
＝-21/7
＝-3