1, a two-digit number? Is 9 greater than the sum of the tenth and fourth digits? If you exchange the number in ten digits with the number in one digit? The two-digit number is 27? Did you find this two-digit number? If a commodity is sold at a 10% discount on the basis of pricing, it can get a profit of 20%? If you sell it at a 20% discount, you can make a profit 10 yuan? What is the price of this product? 3. Does a factory have 120 production workers? Can each worker produce 25 bolts or 20 nuts every day? What if a bolt and two nuts form a set? So how many workers are arranged to produce bolts every day? How many workers produce nuts? In order to make up the most sets of products produced every day? 4. There are three gas stations, A, B and C, in turn, on an expressway? The distance from a to b is 120km? The distance from B to C is also 120km? Two criminal gangs robbed two gas stations, A and C, and fled the scene at the same speed along the expressway after committing the crime? After receiving the command from the command center, the two patrol cars on standby immediately drove to the gas stations A and C at the same speed? As a result, after 1 hour, the gang was stopped by an oncoming patrol car on its way to Bali? And the other gang was chased by another patrol car three hours later? How fast are patrol cars and criminal gangs?