To calculate winnings on fractional odds, multiply your bet by the top number (numerator), then divide the result by the bottom (denominator). So a $10 bet at 5/2 odds is (10 * 5) / 2, which equals $25. A $10 bet at 2/5 odds is (10 * 2) / 5, which is $4.
You can also check out our WILLPAYS for the tracks you are betting on to see what your bet combination will pay before the race goes off.