The owner of an apartment purchased 1 window screen, 1 door handle, and 1 ceiling fan for her apartment. The regular price of the window screen was 80% greater than the regular price of the door handle, and the regular price of the ceiling fan was twice the sum of the regular prices of the window screen and the door handle. The 3 items were sold at a 50% discount off their regular prices. The total price that the owner paid for the 3 items, excluding tax but after the 50% discount, was $50.40. What was the regular price of the door handle?