You need to get the lowest common denominator first, this would be 24 (8 x 3 and 12 x 2)
So multiple he top and bottom to get the denominator to 24
For 5/8: 5 x 3 = 15 and 8 x 3 = 24
For 11/12: 11 x 2 = 22 and 12 x 2 - 24
so you have 15/24 and 22/24
Then you add the numerators together 15 + 22 = 37, to become 37/24 and because 37 is prime 37/24 is simplest terms
