Solution

Sealed Solution Maria Globa

First name
Maria Globa
School
Northcross Intermediate
School's Twitter handle
N/A
Country
Age
12

3-1+2
7-0+7
8-5+3
13-4+9
14-6+8
envolope 8- 3+5

However, I do not think there are many solutions because there are only two ways to get 3, namely 3+0 and 1+2. You have to get all the envelopes to sum up correctly to equal my desired result, 3+5.