AICE Thinking Skills

200 boxes of copier paper have to be delivered to the office building in which I work. I have been instructed to move them all from the ground floor to the storeroom on the 9 floor. Each box weighs 12.5 kilograms, and I weigh 85 kilograms. The lift I will be using has a load limit of 425 kilograms. There is nobody available to help ale, and I do not intend to use the stairs at all. Assuming that I have the lift to myself throughout, how many trips up to the 9th floor will I have to make