Why don't you write the definition of an equivalence relation and start proving it in this case? There are several steps that can be done almost without thinking.
please help me again! the binary relations P on Z x Z+ is defined as
(x1,y1)P(x2,y2) <=> x1 x y1 =x2 x y1
for all x1,x2 belong to Z and y1,y2 belong to Z+
prove that this is an equivalence relation and specify the equivalence class
[(2,3)] as induced by P
thank you very much!