Which of these (x,y)(x, y)(x,y) satisfy xy=5xy = 5xy=5?
(1,5)(1, 5)(1,5)
(5,1)(5, 1)(5,1)
(−1,−5)(-1, -5)(−1,−5)
(2,2.5)(2, 2.5)(2,2.5)