I've made this equation 2 + x = y. It's this way because a charge (2) is an additional (+) fee to the original cost (x, since the cost isn't exactly known.). Y (because it isn't a known value yet) equals the total (yet another word indicating the operation addition) cost.
Plug in anything for x to find out your y. Let's take 7. 2 + 7. 2 + 7 = 9. x = 7 and y = 9. Format to the ordered pair form: (x,y).Therefore an ordered pair of this relationship could be (7, 9).