If x=12, then 2x-5=19. so i don't understand me our ? ? ?

Ure answer for ure question is 
x=12 so u multiply 2*12=24-5=19
24-5=19

First, let's input the x value into the equation:

          2x - 5 = 19
      2(12) - 5 = 19
        24  - 5  = 19
                19 = 19

As you can see, this works! Therefore, the x value is correct. 

Hope this helps!

+1,000)=g7e=mc2-g=7 because if you know algebra you should know g=7 to get your answer