a, (9.x + 2). 3 = 60
9x + 2 = 60 : 3
9x + 2 = 20
9x = 20 - 2
9x = 18
x = 18 : 9
x = 2

b, 71 + (26 - 3x) : 5 = 5^2 . 3
71 + (26 - 3x) : 5 = 25 . 3
71 + (26 - 3x) : 5 = 75
(26 - 3x) : 5 = 75 - 71
(26 - 3x) : 5 = 4
26 - 3x = 4 . 5
26 - 3x = 20
3x = 26 - 20
3x = 6
x = 6 : 3
x =2

a, ( 9.x +2 ).3 = 60                                            b,
    ( 9.x +2 )    = 60:3
     ( 9.x +2)     =20
     9.x              =20-2
      9.x              =18
       x               = 18:9
       x               =2

b) 71 + ( 26 - 3x):5 = 5^2.3
71 +     ( 26 - 3x):5 = 75
=>  ( 26 - 3x):5 = 4
=>  ( 26 - 3x) = 20
=> 3x = 6
=> x = 2 
c) 44 - 7x = 3^4: 3^2    
=> 44 - 7x = 9
=> 7x = 35
=> x = 5
d) 5^( x + 1) + 2.5^2 = 5^2.3
=> 5^( x + 1) + 50 = 75
=> 5^( x + 1) = 25
=> 5^( x + 1) = 5^2 
=> x + 1 = 2
=> x = 1 

a)$$\begin{gathered} (9x+2).3=60 \\ \iff (9x+2)=20\iff 9x=18\Rightarrow x=2 \end{gathered}$$
Vậy x=2
b,
$$\begin{gathered} 71+(26-3x)÷5=5^2.3 \\ \iff (26-3x)÷5=25.3-71 \\ \iff (26-3x)÷5=4 \\ \iff 26-3x=20 \\ \iff 3x=6\iff x=2 \end{gathered}$$
Vậy x=2
c) 44-7x=$3^4÷3^2$
$\iff$44-7x=9
$\iff$7x=35$\Rightarrow$x=5
Vậy x =5
d,$5^{x+1}+2.5^2=5^2.3$
$$\begin{gathered} \iff 5^{x+1}=5^2.3-5^2.2 \\ \iff 5^{x+1}=5^2 \\ \Rightarrow x+1=2 \\ \iff x=1 \end{gathered}$$
Vậy x=1
 

a ) ( 9 . x + 2 ) . 3 = 60
<=> 27x + 6 = 60
<=> 27x = 54
<=> x = 2
b ) 71 + ( 26 - 3 . x ) : 5 = 5^2 . 3
<=> 71 + ( 26 - 3 . x ) : 5 = 75
<=> ( 26 -3 . x ) : 5 = 4
<=>  26 - 3 . x = 20 
<=> 3x = 6
<=> x = 2
c ) 44 -7 . x = 3^4 : 3^2
<=> 44 - 7 . x = 9
<=> 7x = 35
<=> x = 5

(9 * x + 2) * 3 = 60
9 * x + 2 = 60 : 3
9 * x + 2 = 20
9 * x = 20 - 2 
9 * x = 18
x = 18 : 9
x = 2
Vậy x = 2