Question

a, 315+(125-x)=435

b,5×(x-12)=120

c,(3x-7):2=28

Answer 1

a, 315+(125-x)=435

     125-x=435-315

     125-x=120

         x=125-120=5

b, 5(x-12)=120

    x-12=120:5

    x-12=24

x=24+12=36

c, (3x-7):2=28

  3x-7=28.2

  3x-7=56

  3x=56+7

 3x=63

x=63:3=21

Answer 2

a, 215+(125-x)=435

=>125-x=435-315

=>125-x=120

=>x=125-120

=>x=5

b,5x(x-12)=120

=>x-12=120:5

=>x-12=24

=>x=24+12

=>x=36

c,(3x-7):2=28

=>3x-7=28x2

=>3x-7=56

=>3x=56+7

=>3x=63

=>x=63:3

=>x=21

Answer 3

a, 125-x =435-315=120

x=125-120=5

b, x-12=120:5=24

x=24+12=36

c, 3x-7=28x2=56

3x=56+7=63

x=63:3=21