2p-b=c-ap
2p+ap=c+b
p(2+a)=c+b
So, p=(c+b)/(2+a)
Judging by the question you have provided I came to the conclusion that you have already solved your own problem!
If the goal is to find X when X=-15 then your answer for X should be -15!
If this is not the entire equation please post the entire one!
Hope this helped!
-Blake
You left out the 9 in the whole equation. The 1st step you had right you just forgot to put +9. 2nd step you are combining the like terms and get 11-26x=-34x+40. Step 3: you are trying to isolate the x on one of the sides. You need to switch the 11 over to the 40 and get 29. Move -34x over to -26x and get 8x. Step 4 all you are doing in dividing 8 from both sides and get 5.