( 25 . 4 + 65 . 7 ) : 5 - 2 . ( 152 : 8 - 320 : 16 )

= ( 100 + 455 ) : 5 - 2 . ( 19 - 20 )

= 555 : 5 - 2 . ( -1 )

= 111 - ( -2 )

= 113

ket qua la : 515/516

a: \(\dfrac{-3}{25}\cdot\dfrac{4}{17}\cdot\dfrac{5}{-3}\cdot\dfrac{17}{2}=\dfrac{4}{17}\cdot\dfrac{17}{2}\cdot\dfrac{3}{25}\cdot\dfrac{5}{3}=2\cdot\dfrac{1}{5}=\dfrac{2}{5}\)

b: \(=-\dfrac{8}{15}\cdot\dfrac{13}{16}\cdot\dfrac{30}{13}=\dfrac{-8}{15}\cdot\dfrac{15}{8}=-1\)

c: \(=\dfrac{3}{11}\left(\dfrac{2}{9}\cdot\dfrac{-8}{33}+\dfrac{7}{9}\right)=\dfrac{3}{11}\cdot\dfrac{215}{297}=\dfrac{2015}{1089}\)

a) (125 - x) + 25 = 98

125 - x = 98 - 25

125 - x = 73

x = 125 - 73

x = 52

b) 100 : (x + 20) = 68 : 34

100 : (x + 20) = 2

x + 20 = 100 : 2

x + 20 = 50

x = 50 - 20

x = 30

c) (3x + 12) . 5 = 25 . 4 - 10

(3x + 12) . 5 = 100 - 10

(3x + 12) . 5 = 90

3x + 12 = 90 : 5

3x + 12 = 18

3x = 18 - 12

3x = 6

x = 6 : 2

x = 3

d) 210 : (2x - 3) - 20 = 10

210 : (2x - 3) = 10 + 20

210 : (2x - 3) = 30

2x - 3 = 210 : 30

2x - 3 = 70

2x = 70 + 3

2x = 73

x = 73/2

a, ( 125 - x ) + 25 = 98

⇒ 125 - x = 73

⇒ x = 52.

Vậy..

b, 100 : ( x + 20 ) = 68 : 34

⇒ 100 : ( x + 20 ) = 2

⇒ x + 20 = 50

⇒ x = 30

Vậy...

c, ( 3 . x + 12 ) . 5 = 25 . 4 - 10

⇒ ( 3 . x + 12 ) . 5 = 90

⇒ 3 .x + 12 = 18

⇒ 3x = 6

⇒ x = 2.

Vậy...

d, 210 : ( 2 .x - 3 ) - 20 = 10

⇒ ( 2 .x - 3 ) - 20 = 21

⇒ 2x - 3 = 41

⇒ 2x = 44

⇒ x = 22.

Vậy..

\(\Leftrightarrow20+8\left(x+3\right)=100\\ \Leftrightarrow8\left(x+3\right)=80\\ \Leftrightarrow x+3=10\\ \Leftrightarrow x=7\)

1) x - 18 : 3 = 12

x - 6 = 12

x = 12 + 6 

x = 18

2) ( x : 3 ) - 18 = 12

x : 3 = 12 + 18

x : 3 = 30

x = 30 x 3

'x = 90

3) ( x - 3 ) : 4 = 7

x - 3 = 7 x 4

x - 3 = 28

x = 28 + 3 

x = 31

4 ) ( x : 15 ) - 3 = 25 x 4

( x : 15 ) - 3 = 100

x : 15 = 100 + 3

x : 15 = 103

x = 103 x 15

x = 1545

5) ( x - 25 ) : 9 = 0

x - 25 = 0 x 9

x - 25 = 0

x = 0 + 25

x = 25

6) 34 : ( x - 8 ) = 34

x - 8 = 34 : 34

x - 8 = 1

x = 1 + 8

x = 9

7) ( x + 4 ) x 16 = 80

x + 4 = 80 : 16

x + 4 = 5

x = 5 - 4

x = 1

\(1.x-18:3=12\)

\(x-18=12.3\)

\(x-18=36\)

\(x=36+18\)

\(x=54\)

a) 125 . 10 = 1 250

b) 2 021 . 100 = 202 100

c) 1 991 . 25 . 4 = 1 991 . (25 . 4) = 1 991 . 100 = 199 100

d) 3 025 . 125 . 8 = 3 025 . (125 . 8)

= 3 025 . 1 000 = 3 025 000