-20 + x =10

Question

Don't know

Answer 1

 

-20 + x  is the same as x - 20…  so think "some number x minus 20 is 10"

 

  x - 20 = 10

  x - 20 + 20 = 10 + 20   (we can add any number to both sides without

                                      changing the equality)

 

   x + 0 = 30                   Goal is virtually always to isolate the unknown by itself

                                     

 

That's all there is to it.