So then what you want to do is 105 for the grams, minus the box, which is 15 you then get 95, then do that divided by ten because you that's how many markers. You then would get 9.5. So too double check do 9.5*10 to see if that's the marker amount and add 15.
Each crayon weighs 9 grams. First, if the box is 15 grams, you need subtract 105 with 15, which is 90. Then, divide 90 by 10(the amount of crayons), and you get 9, so each crayon weighs 9 grams
