This notation of odds seems rather strange to me (I know it is apparently standard since I've seen it a few times). Am I right in supposing that the apparent subtraction "1 - 6" actually means that if you win, you're paid 6 times your bet, and that "7/2" means that you get 3,5 times your bet? Why don't they just always express it as a decimal fraction instead of making people do that calculation by themselves (and swap the numbers and change the subtraction into a division if it is written as "a - b")?

(It is probably obvious I never bet :-))