TASK DEFINITION: You are given a math word problem and you are supposed to apply addition or subtraction mathematical operators on the numbers embedded in the text to answer the following question and then only report the final numerical answer.
PROBLEM: Donna weighs 69 pounds . Willie weighs 51 pounds . How much heavier is Donna than Willie ?

SOLUTION: 18

PROBLEM: Kaleen filled a bucket with 0.75 gallon of water . A few minutes later , she realized only 0.5 gallon of water remained . How much water had leaked out of the bucket ?

SOLUTION: 0.25

PROBLEM: Karin 's science class weighed plastic rings for an experiment . They found that the orange ring weighed 0.08333333333333333 ounce , the purple ring weighed 0.3333333333333333 ounce , and the white ring weighed 0.4166666666666667 ounce . What was the total weight of the plastic rings ?

SOLUTION:
0.8333333333333334