Kirk made a large batch of snack mix to sell during a football game. The snack mix was made of nuts, pretzels, chocolate chips, and raisins. The batch weighed 253 ounces altogether. The snack mix contained twice as many ounces of pretzels as nuts. It contained twice as many ounces of raisins as pretzels, and the same number of ounces of chocolate chips and raisins. How many ounces of raisins did the snack mix contain?