many thanks Michael, the command do it ,but I have problems with the following, if run the command Nearest[ {{290,230},{250,170},{180,140}},{280,105}] returns {290,230} but I want the value {250,170},ie I want to always return the closest value but less than the first number I enter as an argument of the function, in this case {280,105} the first number is 280 and I want the closest value but less ie the 250, Is there any way?
With another example I hope to explain,
Nearest[ {{425,218},{383,178},{529,431},{690,571}},{412,280}] returns {425,218} and I want the closest but less {383,178}, I hope you can help me