The graph of the relation between x and y is as shown in attached figure
By applying the vertical line test we find that the relation is not a function because there are two points which are (1,-1) , (1,3) have the same value of x with different values of y which contradicts with with the rule of function.
If you multiply 36 by four since there are 4 wheels for skateboard you will get 144. That number is the total number of wheels you need to order and since they come in packs of 20 what you need to do is divide 144 by 20 and you will get 7.2. So obviously you can't order 7.20 packs of wheels so this means that 8 packs of wheels must be bought in order to ensure that all of the skateboards get wheels on them. The answer is 8.