1) Associative property under addition: (a + b) + c = a + (b + c)
Substitute: (12 + 6) + -10 = 12 + (6 + -10)
Add (parentheses): 18 - 10 = 12 + -4
Add: 8 = 8
Therefore the associative property under addition is true
2) Distributive property of multiplication over subtraction: a(b - c) = ab - ac
Substitute: 12(6 - -10) = (12 * 6) - (12 * -10)
Simplify: 12(16) = (72) - (-120)
Simplify: 192 = 192
Therefore the distributive of multiplication over subtraction is true.