3.4x10.9+34-0.34x19=3.4x10.9+34-3.4x1.9=34+3.4x(10.9-1.9)=34+3.4x(10-1)=34+34-3.4=64.6
3.4x10.9+34-0.34x19=0.34x109+0.34×100-0.34x19=0.34×（109+100-19）=0.34×190=64.6
