a) 35 x 2 x 9 x 5

= (35 x 9) x (2 x 5)

= (35 x 10 - 35) x 10

= (350 - 35) x 10

= 315 x 10 = 3150

b) 24 x 71 + 71 x 75 + 71

= 71 x (24+75+1)

=71 x 100

= 7100

giúpppppppppppppppppppppppppppppppppppp

=> 26 - 3x = 75 - 71

<=> 26 - 3x = 4

<=> 22 = 3x

<=> x = \(\dfrac{22}{3}\)

Vậy ...

71 + (26 - 3x) = 75
26 - 3x = 75 - 71
26 - 3x = 4
-3x = -22
x= -22/-3
=> x = 22/3
Vậy...

\(71+\left(26-3x\right)=75\) 

   \(71+26-3x=75\) 

                   \(3x=71+26-75\) 

                   \(3x=22\) 

                     \(x=22:3\) 

                     \(x=\dfrac{22}{3}\)

71 + ( 26 - 3 . x ) ; 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

71+(26-3.x):5=75

71+(26-3x)=75.5=375

26-3x=375-71=304

3x=26-304=-278

x=\(\frac{-278}{3}\)

71 + (26 - 3 . x):5 = 75

 26 -3 .x : 5 = 75-71

26 - 3 .x : 5 =   4

      3 .x : 5 = 26 - 4

      3 .x : 5 =   22

      3 .x      = 22 . 5

      3.x       =    110

        x       =  ?

d) 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 = 2

Vậy x = 2

( 26 - 3x ) : 5 = 75 - 71

( 26 - 3x ) : 5 = 4

26 - 3x = 4 x 5

26 - 3x = 20

3x = 26 - 20

3x = 6

x = 6 : 3

x = 2

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

x = 2 nha bn

k giùm mk nha các bn

>_< học tốt

70. Everybody is here now, ___aren't they_______?

71. There is nothing wrong, _____isn't there_____?

72. Mike mustn’t come late, ____must he______?

73. She is collecting stamps, ____isn't she______?

74. They often watch TV in the afternoon, ______don't they____?

75. David has cleaned your bike, ____hasn't he______?

76. John and Max don't like Maths, ____do they______?

77. Peter played handball yesterday, ______didn't he____?

78. Mary didn't do her homework last Monday, ____did she______?

79. Lewis could have bought a new car, ______couldn't he____?

80. The train is arriving on time, ____isn't it______?

81. Kevin spent all his money yesterday, ____didn't he______?

82. He had hardly left the office when the telephone rang, _____hadn't he_____?

83. Max'd better stay here for a week, ____shouldn't he______?

84. Nothing was damaged during the storm, ______was it____?

85. Mrs. Black doesn't believe her son is able to draw such a picture, _____does she_____?

86. He comes late sometimes, ____doesn't he______?

87. He failed to do anything last weekend, ____didn't he______?

88. The Smiths hardly ever go on travel, __does they______?

89. Jack and Jill went up the hill, ____don't they______?

90. There are seven days in a week, ________aren't there__? 

.

.                                                                                                               .

\(\left(26-3x\right):5+71=75\)

\(\left(26-3x\right):5=4\)

\(26-3x=20\)

\(3x=6\)

\(x=2\)

(26-3x):5+71=75

(26-3x):5=4

26-3x=20

3x=6

x=2