25 - 45 = 16 - 26
16 - 36 + 81/4 = 25 - 45 + 81/4
42 - 2 х 4 х 9/2 + (9/2)2 = 52 - 2 х 5 х 9/2 + (9/2)2 (4 - 9/2)2 = (5 - 9/2)2 4 - 9/2 = 5 - 9/2 4 = 5
2 х 2 = 5