It's not
5 miles is slightly longer than 8 km.
no because 5 over 6 is closer to a whole than 5 over 12
No, it is bigger than both of them.
There are 10 millimetres in one centimetre. Therefore, 8 centimetres is equal to 8 x 10 = 80 millimetres. Subtracting 5 millimetres from this gives 80 - 5 = 75 millimetres. 8 centimetres is therefore 75 millimetres, or 7.5 centimetres, longer than 5 millimetres.
5 over 6 is greater than 1 over two