Answer:
B.) 
Step-by-step explanation:

A negative and a negative equals a positive. Remove parentheses and simplify

Done.
Answer:
Multiply both sides by 3, then subtract 6 from both sides
Step-by-step explanation:
d + 6 / 3 = 6 (multiply both sides by 3)
d + 6 = 18 (subtract 6 from both sides)
d = 12
Answer:
C) {(12,3), (11,2), (10,1), (9,0), (8,1), (7,2), (6,3)} Is a function.
Step-by-step explanation:
The easiest way to tell if a Relation is a Function (in my opinion) is the Verticle Line test. Use your pairs and put them in a graph. Then connect the dots, and if your line at any point touches the graph once, then your Relation is a Function. If it touches the graph more than once, it is not a Function.
Regards!