19又13/14×（-11）,
=(20-1/1/14)*(-11)
=-11*20-11*1/14
=-220-11/14
=-220又11/14
-99又23/24×18,
=(-100+1/24)*18
=-100*18+1/24*18
=-1800+3/4
=-1799-1/4
=-1799又1/4
-13×2/3-0.341×2/7+1/3×（-13）-5/7×0.34+3
=-13×2/3+1/3×（-13)-0.341×2/7-5/7×0.34+3
=-13*(2/3+1/3)-0.341*(2/7+5/7)+3
=-13-0.341+3
=-13.341+3
=-10.341