Amy does some special operations when she sums up numbers. If the answer is greater than 100, she will subtract 10 from it; if the answer is lower than 100, she will add 10 to it; otherwise, no change will be made to the answer.

For example:
87 + 16 ( 93
12 + 37 ( 59
If after two summations, the answer she gets is 100, find the sum of possible values of the correct.
The Answer: 500

Please help me to solve this oneπŸ˜’πŸ™πŸ™

Assuming we are dealing only with positive integers.

Not really sure what you are trying to find since "find the sum of possible values of the correct"
makes no sense

however, since her "answer" was 100, the actual real answer could have
been 110 or 90
to get 90, we could have had:
1+89, 2+88, .... , 89+1 . There would be 89 of these
to get 110, we could have had
1 + 109, 2+108, ... , 109+1, there are 109 of these
for a total of 198

Since you are stating that the answer is 500, looks like I am not
interpreting your question correctly.