Ok so what you want to do this split the numbers up into sections for example 15-20 find numbers through those numbers. Then count how many there are. After putting them in the blank space and the use the graph to put the same number in. Hope this helps!
Since you know that the pet store has 9 dog leashed, and we know that they have 8 fewer dog leashes than dog collars we can just add 8 to 9 to get 17 dog collars
