1. Answer: A two digit number whose sum of tens and ones is 12. If 54 is subtracted from this two digit number, the positions of the two digit numbers are swapped. Find the original two digit number.
Answer: 75
Answer: There are four couples sitting in a row to take a photo. How many different sitting styles are there that make each couple sit together?
Answer: 24
Answer: Xiaoming rides his bicycle across a bridge, with a speed of 12 kilometers per hour when getting on the bridge and 24 kilometers per hour when getting off the bridge. Moreover, the distance traveled on and off the bridge is equal and there is no pause in between. What is Xiaoming's average speed across the bridge in kilometers per hour?
Answer: 16