5 kg of peaches is X yuan, 1 kg is X yuan, and one yuan can buy X kg of peaches. This is a very simple mathematical problem, which can be solved as long as the relationship between the total amount and the unit price is clarified.

Mathematics is a subject that studies concepts such as quantity, structure, change, space and information. Mathematics is a universal means for human beings to strictly describe and deduce the abstract structure and mode of things, and can be applied to any problem in the real world.