Rosita's backpack weighs 20 pounds. what does rosita weigh?

To determine Rosita's weight, we need additional information. The weight of her backpack, which you mentioned, is 20 pounds, but this does not provide us with Rosita's actual weight. To find out Rosita's weight, we would need to either have another piece of information or use an estimation based on factors like age, height, body type, or personal background. Without this information, we cannot determine Rosita's weight.