Final answer:
By dividing Ann's share of $900 by her ratio portion of 9 and finding the value of one part as $100, we are able to calculate the total sum shared between the friends, which amounts to $2100.
Step-by-step explanation:
The problem involves dividing a sum of money among three friends: Kim, Trisha, and Ann, based on a specific ratio. To solve this, we need to establish what portion of the total sum Ann received and then use that information to calculate the total sum. Since Ann's share is described as 9 parts of the total ratio of 5:7:9, we can determine the value of one part by dividing the amount Ann received, $900, by 9. This gives us the value of one part of the ratio, which we can then scale up to find the total sum shared among the friends.
The calculation is as follows:
- Value of one part: $900 ÷ 9 = $100 per part
- Total ratio parts: 5 + 7 + 9 = 21 parts
- Total sum: 21 parts × $100 per part = $2100
Therefore, the total sum of money that was shared between Kim, Trisha, and Ann is $2100.