Bài 2:
27 x 75 + 25 x 27 - 150
=27(75+25)-150
=2700-150
=2550
12:{400:[500-(125+25.7)]}
=12:{400:[500-(125+175)]}
=12:{400:[500-300]}
=12:{400:200}
=12:2
=6
13.17-256:16+14:7-1
=221-16+2-1
=206
18.3+182+3(51:17)
=54+182+3.3
=54+182+9
=245
15-25.8:(100.2)
=15-1000:200
=15-5
=10
25.8-12.5+170:17-8
=1000-60+10-8
=942
Bài 4
70-5(x-3)=45
5(x-3)=25
x-3=5
x=8
12+(5+x)=20
5+x=8
x=3
130-(100+x)=25
100+x=105
x=5
175+(30-x)=200
30-x=25
x=5
5(x+12)+22=92
5(x+12)=70
x+12=14
x=2
95-5(x+2)=45
5(x+2)=50
x+2=10
x=8
10+2x=4^5:4^3
10+2x=16
2x=6
x=3
14x+54=82
14x=82-54
14x=28
x=2
15x-133=17
15x=150
x=10
155-10(x+1)=55
10(x+1)=100
x+1=10
x=9
6(x+2³)+40=100
6(x+8)=60
x+8=10
x=2
2²(x+3²)-5=55
4(x+9)=60
x+9=15
x=6