You can put this solution on YOUR website! There are numerous definitions for a function but in this case we use the definition that each x value is associated the only 1 y value. Each x value 3, 4, 10 and 12 has 6 as the y value. We didn't say the y value had to change. It is a function. If any of the x values has two different y values like a (3,4) and a (3,5) then it wouldn't be a function. That's not the case for this collection of ordered pairs which is a function.