There are 8 numbers in all. There are 3 orange odd numbers, one blue odd number, 3 blue even numbers and one white even number. The chances of a blue even are therefore 3/8 and the chances of an odd orange are also 3/8. So 6 combinations consist of both of these sets added together, making the combination of one or the other 6/8 or 3/4=0.75 or 75%.