− x − 8 5 = 1 20 − 1 10 = > x − 8 5 = − 1 20 = > x = − 1 20 + 8 5 = > x = 31 20

a, { 36; 48; 60; 72; 84}

b, { 15; 30; 45; 60; 75; 90} 

c, { 1; 2; 3; 4; 6; 9; 12; 18; 36} 

2175,882353

2295+15/17-120=2175/15/17

27 x 85 + 15 : 17 - 120

= 2 295 + 15/17 - 120

= 39030/17 - 120

= 36990/17

a) 15 x 141 + 59 x 15

= 15.(141 + 59) 

= 15.200

= 3000

b) 17 x 85 + 15 x 17 - 120

= 17(85 + 15) - 120 

= 17.100 - 120

= 1700 - 120

= 1580

15*(141+59)

=15*200

=3000

17*(85+150)-120

=17*100-120

=1700-120

=1580

a)15.141+ 59.15

=15.(141+ 59)

=15.200

= 3000

b)17.85+ 15.17- 120

=17.(85+ 15)   - 120

=17.  100        - 120

=    1700         - 120

=            1580

\(24\times\left(15+30+85-120\right)\div16\)

\(=24\times10\div16\)

\(=15\)

\(140-180\times\left(47-90+43+7\right)\)

\(=140-\left(180\times7\right)\)

\(=140-1260\)

\(=-1120\)

khó quá đi ! 

24.(15+30+85-120):16

=24.10:16

=240:16

=15

140-180.(47-90+43+7)

=140-180.7

=140-1260

=-1120

1. a) 17.85 + 15.17 - 120

= 17.( 85 + 15) - 120

= 17. 100 -120

= 1700 - 120

= 1580

b) 20 - [ 30 - (5 - 1)² ]

= 20 - [ 30 - 4² ]

= 20 - [ 30 - 16 ]

= 20 - 14

= 6

2. a) 70 - 5.(x - 3) = 45

              5.(x - 3) = 70 - 45

              5.(x -3) = 25

                 x - 3 = 25 : 5

                 x - 3 = 5

                 x = 5 + 3

                 x = 8 

b) 10 + 2.x = 4⁵ : 4³

    10 + 2.x = 4²

    10 + 2.x = 16

           2.x = 16 - 10

          2.x = 6

             x = 6 : 2

            x =3

1)a:17.85+15.17-120=17.(85+15)-120=17.100-120=1700-120=1580

b: 20-[30-(5-1)^2 = 20-[30-4^2]=20-(30-16)=20-15=5

2)

a:  70-5(x-3)=45

   5(x-3) = 70-45=25

   x-3 = 25:5=5

   x= 5+3=8

b:  10+2x = 4^5:4^3

   10+2x = 4^2

10+2x = 16

2x = 16-10=6

x = 6:2=3

1, Thực hiện phép tính :

a) \(\left(-37\right)+4\cdot\left|-6\right|\)

\(=-\left(37\right)+4\cdot6\)

\(=-37+24\)

\(=13\)

b) \(17\cdot85+15\cdot17-120\)

\(=17\cdot\left(85+15\right)-120\)

\(=17\cdot100-120\)

\(=1700-120\)

\(=1580\)

2, Tìm x :

a) \(x-12=-20\)

\(x=-20+12\)

\(x=8\)

b) \(2014\cdot\left(x-12\right)=0\)

\(\Rightarrow\text{ }x-12=0\)

\(x=0+12\)

\(x=12\)

B1 : a) \(\left(-37\right)+4|-6|\)

\(=\left(-37\right)+24\)

\(=-13\)

b) 17 . 85 + 15 . 17 - 120

= 17 . ( 85 + 15 ) - 120

= 17 . 100 - 120

= 1700 - 120

= 1580

B2 : a) x - 12 = - 20 

            x        = - 20 + 12

            x        = - 8

b) 2014( x - 12 ) = 0

               x - 12 = 0 : 2014

               x - 12 = 2014

               x        = 2014 + 12

               x        = 2026

x + 30 = 10 x 85 + 85 x 9

x + 30 = 1615

        x  = 1615 - 30

        x  = 1585

x+30=10x85+9×85

x+30=85×(10+9)

x+30=85×19

x+30=1615

x=1615-30

x=1585

x + 30 = 10 x 85 + 85 x 9

x + 30 = ( 10 + 9 ) x 85

x + 30 = 19 x 85

x + 30 = 1615

       x = 1615 - 30

       x = 1585