71-(33+x)=26
33+x=71-26
33+x=45
x=45-33
x=12
Vậy x=12
45-(x-9):2=6
(x-9):2=45-6
(x-9):2=39
x-9=39.2
x-9=78
x=78+9
x=87
Vậy x=87
\(77-\left(33+x\right)=26\\ \Rightarrow33+x=77-26=51\\ \Rightarrow x=51-33=18\\ 45-\left(x-9\right):2=6\\ \Rightarrow\left(x-9\right):2=45-6=39\\ \Rightarrow x-9=39\cdot2=78\\ \Rightarrow x=78+9=87\)
a 3x +81
b 3mũ4 .3x = 3mũ7
c 3x+ 25= 26.2mũ2 + 2.3mũ 0