7 + 1 + 2 = 321 4 + 5 - 1 = 416 9 + 5 - 4 = 19 4 + 2 + 3 =?

7 + 1 + 2 = 321 4 + 5 - 1 = 416 9 + 5 - 4 = 19 4 + 2 + 3 =?

520