bài 1
a, 128.46+128.30+128.24 b,62.75+62.50-25.62
=128.(46+30+24) =62.(75+50-25)
=128.100 =62.100
=12800 =6200
c,29.87-29.23+64.71 d,48.19+115.48+52.134
=29.(87-23)+64.71 =48.(19+115)+52.134
=29.64+64.71 =48.134+52.134
=64.(29+71) =134.(48+52)
=64.100 =134.100
=6400 =13400
e,19.27+47.81+19.20 bài 2:
=19.(27+20)+47.81 720:[41-(x-5)]=23.5
=19.47+47.81 720:[41-(x-5)]=115
=47.(19+81) 41-(x-5)=6.6/23
=47.100 x-5=39.10/23
=4700 x=44.10/23
vậy .......