0.7×1又4/9+2又3/4×﹙﹣15﹚+0.7×5/9-1/4×15

0.7×1又4/9+2又3/4×﹙﹣15﹚+0.7×5/9-1/4×15
0.7×1又4/9+2又3/4×﹙﹣15﹚+0.7×5/9-1/4×15

0.7×1又4/9+2又3/4×﹙﹣15﹚+0.7×5/9-1/4×15
=0.7×1又4/9+0.7×5/9+11/4×(-15)-1/4×15
=0.7×(13/9+5/9)+(2又1/2+1/4)x(-15)一1/4x15
=1.4+2又1/2x(-15)+1/4x(-15)-1/4x15
=1.4+(-37.5)+(-15/4)+(-15/4)
=-36.1+7.5
=-20.6