Answer:
1. 18
2. 15
3. Symmetric Property
Step-by-step explanation:
1. 8 + 10 = 18
2. Following symmetric prop. of eq. would mean that since 8 + 10 = 15 + 3 and 8 + 10 = 18, 15 + 3 = 18 as well
3. Symmetric Property of Equality states that if a = b, then b = a
