Đáp án:+Giải thích các bước giải:
`text(Bài 1:)`
`a)` `1 13/15.0,75-(8/15+25%)`
`=28/15.(3)/4-(8/15+1/4)`
`=7/5-8/15-1/4`
`=84/60-32/60-15/60`
`=(84-32-15)/60`
`=37/60`
`b)` `0,75-43/80:(-4/5+2,5.(3)/4)`
`=3/4-43/80:(-4/5+5/2.(3)/4)`
`=3/4-43/80:(-4/5+15/8)`
`=3/4-43/80:(-32/40+75/40)`
`= 3/4 - 43/80 : 43/40`
`= 3/4 - 1/2`
`=3/4-2/4`
`=1/2`
`text(Bài 2:)`
`A=-7/813+496.(-7/813)+(-7/813).316`
`=-7/813.(1+496+316)`
`=-7/(813).813`
`=-7`
`-----`
`B=-9/10.(5)/14+1/10.(-9)/2+1/7.(-9/10)`
`=-9/10.(5)/14+(-9/10).1/2+1/(7).(-9/10)`
`=-9/10.(5/14+1/2+1/7)`
`=-9/10.(5/14+7/14+2/14)`
`=-9/10.14/14`
`=-9/10.1`
`=-9/10`
`text(Bài 3):`
`a)3 1/2+2x=5 1/3:2 2/3`
`<=>7/2+2x=16/3:(8)/3`
`<=>7/2+2x=16/3.(3)/8`
`<=>7/2+2x=2`
`<=>2x=2-7/2`
`<=>2x=4/2-7/2`
`<=>2x=-3/2`
`<=>x=-3/4`
`Vậy` `x=-3/4`
`b)` `(4 1/3+3x).2 3/5=2/3-5`
`<=>(13/3+3x).13/5=2/3-15/3`
`<=>13/3+3x=-13/3:13/5`
`<=>13/3+3x=-5/3`
`<=>3x=-5/3-13/3`
`<=>3x=-18/3`
`<=>3x=-6`
`<=>x=-2`
`Vậy` `x=-2`
