a)13+3x=55 =>3x=42=> x=14
b)5x-9=116 =>5x=125=> x=25
c)72-6/x=66 =>6=6x =>x=1
d)x/11+4=21 =>x/11=17 x=17/11
e)(4x-24).27=0 =>4x-24=0 =>x=6
f)x-105/21=15 =>x=15+105/21=>x=20
g)(x-105)/21=10 =>x-105=210 => x=315
h)(x-5)(x-7)=0 =>x=5 hoặc x=7
cho mk hay nhất nhé!