\(=240+390+560+750=1940\)

b) 12 x 20 + 13 x 30 + 14 x 40 + 15 x 50

=(12x20) x (13x30) + (14x40) x (15x50)

=1940

10 x 5 + 5 x 10

c1 : 10 x (5 + 5)

        = 10 x 10

        = 100

c2 : (10 + 10) x 5 

       = 20 x 5

       = 100

50 + 10 + 90 + 50 + 30 + 60 + 10 + 70 + 50 + 50

c1 : (50 + 50) + (10 + 90) + (30 + 60 + 10) + (50 + 50) + 70

      =  100 + 100 + 100 + 100 + 70

      =   100 x 4 + 70

      = 400 + 70

      = 470

c2: 50 x 4 + (10 + 90) + (70 + 30) + (60 + 10)

     = 200 + 100 + 100 + 70

    = 200 + 100 x 2 + 70

    = 200 + 200 + 70

    = 200 x 2 + 70

     = 400 + 70 = 470

= ( 60 + 50+40+30+20+10 ) x 2000 + 1500

= 210 x 2000 + 1500

=  420000 + 1500

= 421500

= 421500 nha bn, nhớ k mk nha

50 x 2 + 8 x 50

= (2 + 8) x 50

=     10   x 50

=       500

10 + 10 + 10 + 50 + 50 + 10 + 10

= (10 x 5) + (50 + 50)

=     50     +     100

=         150

50 x 2 + 8 x 50 

= 50 x ( 2 + 8 ) 

= 50 x    10 

= 500

10 + 10 + 10 + 50 + 50 + 10 + 10

= 10 x 5 + 50 x 5 

=    50    +   250

=         300

50 : x - 20 : x = 10

(50 - 20) : x    = 10

    30      : x     = 10

                x     =  30 : 10

                x      = 3

50:x - 20:x=10

(50 - 20):x=10

30:x=10

x=30:10=3

Tích nha

\(a,50\%+\dfrac{7}{12}-\dfrac{1}{2}\\ =\dfrac{1}{2}+\dfrac{7}{12}-\dfrac{1}{2}\\ =\left(\dfrac{1}{2}-\dfrac{1}{2}\right)+\dfrac{7}{12}\\ =\dfrac{7}{12}\\ b,2022\times67+2022\times43-2022\times10\\ =2022\times\left(67+43-10\right)\\ =2022\times100\\ =202200.\\ c,125-25:3\times12\)

\(=25\times5-25:3\times12\\ =25\times\left(5-\dfrac{1}{3}\right)\times12\\ =25\times\dfrac{14}{3}\times12\\ =1400\)

a,50%+127​−21​=21​+127​−21​=(21​−21​)+127​=127​b,2022×67+2022×43−2022×10=2022×(67+43−10)=2022×100=202200.c,125−25:3×12

=25×5−25:3×12=25×(5−13)×12=25×143×12=1400=25×5−25:3×12=25×(5−31​)×12=25×314​×12=1400

\(50\%+\dfrac{7}{12}-\dfrac{1}{2}\)

\(=\dfrac{1}{2}+\dfrac{7}{12}-\dfrac{1}{2}\)

\(=\left(\dfrac{1}{2}-\dfrac{1}{2}\right)+\dfrac{7}{12}\)

\(=\dfrac{7}{12}\)

_______________

\(2022\cdot67+2022\cdot43-2022\cdot10\)

\(=2022\cdot\left(67+43-10\right)\)

\(=2022\cdot100\)

\(=202200\)

_____________________

\(10,3+6,9+8,7+13,1\)

\(=\left(13,1+6,9\right)+\left(10,3+8,7\right)\)

\(=20+19\)

\(=39\)

___________________

\(17,58\times43+57\times17,58\)

\(=17,58\times\left(43+57\right)\)

\(=17,58\times100\)

\(=1758\)

tớ ghi sai nên cập nhật lại câu hỏi, phần 3 các bạn trả lời sớm mà bị sai thì bỏ qua cho tớ nhé

 10+20+30+40+50+60+70+80+90

=(10+90)+(20+80)+(30+70)+(40+60)+50

=100 + 100 + 100 + 100 + 50

= 100 x 5 + 50

= 500 + 50 =550

= ( 1 0 + 90) + ( 20 + 80)  + ( 30 + 70) + ( 40 + 6 0) + 50

= 100 + 100 + 100 + 100 + 50

= 400 + 50 

= 450

=2021x100=202100

20x2021x50

=2021x(20x50)

=2021x100

=202100