Câu 3:
a) x-2,5.40=0,8.125 b) (x+12,8).4,5=900
x-100=100 (x+$\frac{128}{10}$).$\frac{45}{10}$=900
x=100+100 (x+$\frac{64}{5}$).$\frac{9}{2}$=900
x=200 x+$\frac{64}{5}$=900:$\frac{9}{2}$
x+$\frac{64}{5}$=200
x=$\frac{936}{5}$(187,2)
c) x:0,25+x.16=20:0,5 d) (x-2,5).8=x.6-4 e) $\frac{x}{15}$=$\frac{2}{5}$
x:$\frac{1}{4}$+x.16=20:$\frac{1}{2}$ 8x-8.2,5=6x-4 5.x=2.15
x.4+x.16=40 8x-20=6x-4 5.x=30
x.(4+16)=40 8x-6x=-4+20 x=6
x.20=40 2x=16
x=2 x=8
Lười đéo làm nx
