Could someone please help me with this question

. EQ2 Let A = N X N, and define a relations R on A by (a, b) R(c, d) if and only if ab = cd. (a) Show that R is an equivalence relation on A. (b) List the elements in the equivalence class [(9, 2)]. (c) Find an equivalence class with exactly two elements. (d) Find an equivalence class with exactly three elements