I will provide a picture for this, as my explanation. If you are at (11,8) and you go up 9, that's 9+8 which is 17. Your 11 is on the x-axis, which goes side to side. 8 is on the y-axis which goes up and down. That is why it is now (11,17)
Step-by-step explanation:
Sorry my writing is messy.
