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.

Example Input: Megan was selling her necklaces at a garage sale . She sold 7 bead necklaces and 3 gem stone necklaces . If each necklace cost 9 dollars , how much money did she earn ?
Example Output: 90

Example Input: Sara had 21 quarters in her bank . Her dad gave her 49 quarters . How many quarters does she have now ?
Example Output: 70

Example Input: A pet store had 12 siamese cats and 20 house cats . During a sale they sold 20 cats . How many cats do they have left ?
Example Output:
12