Answer:
Sydney is 72.
Step-by-step explanation:
It is important to note the word "sum" in the problem. The definition of sum is the product of addition. And to get the inverse of addition you would use subtraction. So you subtract 11 from 83 (83 - 11) which equals 72.
You can check this by adding 72 + 11 and making sure it equals the overall sum of 83 which it does.
So glad I could help! Feel free to comment any questions.
