500 + x = 100 + 500

500 + x = 600

          x = 600 - 500

          x = 1001

300 - x = 300 + 200

300 - x = 500

         x = 300 - 500

         x = -200

400 - x = 200 + 400

400 - x = 600

         x = 400 - 600

         x = -200

k mk nha mk k l

ại ^_^

500 + 100 = 100 + 500

300 + 200 =  300 + 200

400 + 200  = 200 + 400

500+x=100+500

vay x =100

300-x=300+200

vay x= - 200

400-x=200+400

vay x= -200

x + 400 = 500 - 100

x + 400 = 400

x =400 - 400

x = 0

Vậy x = 0

x + 400 = 500 - 100

x + 400 = 400

x = 400 - 400

x = 0

x=0 nha

 bn tk mk nhé

  \(120\)\(+\)\(80\)\(=\)\(500\)\(-\)\(x\)                     \(100\)\(+\)\(100\)\(=\)\(400\)\(-\)\(x\)

            \(200\)        \(=\)\(500\)\(-\)\(x\)                              \(200\)           \(=\)\(400\)\(-\)\(x\)

\(500\)\(-\)\(200\)\(=\)\(x\)                                         \(400\)\(-\)\(200\)\(=\)         \(x\)

           \(300\)          \(=\) \(x\)                                                  \(200\)           \(=\)        \(x\)

120 + 80 = 500 - x

200 = 500 - x

x = 300

100 + 100 = 400 - x

200 = 400 - x

x = 200

120 + 80 = 500 - x

100 + 100 = 400 - x

Ta có : 

120 + 80 = 500 - x

=> 500 - x = 200

=> x = 300

Lại có : 

100+100=400-x

=> 400-x = 200

=> x = 200

750

tk mình nha

x + 50 + 100 = 500 + 400

x + 50 + 100 = 900

x = 900 - 100 - 50

x = 750

k mk mk k lại

150

tk mình đấy 

x + 100 =500

          x = 500 - 100

          x = 400

200 + x = 400

          x = 400 - 200

          x = 200

ai k mk mk k lại ^_^

x+100=500

       x=500-100

       x=400

200+x=400

       x=400-200

       x=200

1) 400 

2) 200 nhé bạn

a)x+400=500-100

 x+400=400

 x=400-400

 x=0

b)x+10=50

  x=50-10

  x=40

x + 400 = 500 - 100

x + 400 = 400

          x = 400 - 400

          x = 0

x + 10 = 50

        x = 50 -10

        x = 40

x+400=500-100

x+400=400

x       =400-400

x       =0

x+10=50

x     =50-10

x     =40

tk mk nha

x+400=500-100

x+400=400

x       =400-400

x       =0

x + 400 = 500 - 100

x + 400 = 400

x = 400 - 400

x = 0

K mk nha

Mk k lại

x + 400 = 500 - 100

x + 400 = 400

x          = 400 - 400

x          = 0

x + 100 = 200 - 300

x + 100 = - 100

          x = 100 - 100

          x = 0

x - 300 = 400 - 500

x - 300 = -100

        x = -100 + 300

        x = 200

k mik mik k lại

x + 100 = 200 - 300

x + 100 = -100

x = -100 - 100

x = -200

x - 300 = 400 - 500

x - 300 = -100

x = -100 + 300

x = 200 

1 bang-200

2bang200