Quick Print Inc. uses plain paper for copying needs. Weekly demand for that paper follows a normal distribution with mean 100 and standard deviation 10 (measured in reams). Each week, a replenishment order is placed with its supplier and the order arrives three weeks later. All copying orders that cannot be satisfied immediately due to the lack of paper are backordered. What order up-to level should be used to achieve at least a 90% in-stock probability? (please use the normal distribution table and round up to the nearest integer)