In order to find the number of empty bins, let's calculate how many packs will be made with the given material.
240 markers can be organized in 240/8 = 30 packs
320 crayons can be organized in 320/8 = 40 packs
336 colored pencils can be organized in 336/8 = 42 packs
In total we have 30 + 40 + 42 = 112 packs
Each bin can hold 8 packs, to in order to hold 112 packs, we need 112/8 = 14 bins.
We have 24 bins. Since 14 will be used, we will have 24 - 14 = 10 empty bins.