The kitchen floor in Jasmine’s house measures 6 m by 4 m. She intends to tile the floor with a selection of red, blue and white tiles, each of which is 20 cm by 20 cm. Katie and Lucy both have floors which are identical in size and shape to Jasmine’s floor. They will both use the same type of tiles on their floors. Jasmine uses red, blue and white tiles in the ratio 4 : 5 : 1. Katie uses red and white tiles only, with half as many red tiles as white tiles. Lucy uses red and blue tiles only, with three times as many blue tiles as red tiles. Jasmine, Katie and Lucy decide to buy all the tiles that they need together. What is the difference between the total number of white tiles and the total number of red tiles that are needed?