Lol this is my first time seeing someone saying I bet no one will answer this. Ok coming back to the topic answers are :-
Initial value = -18
Initial value is the output value or the y variable. Looking in the table the y variable is -18 since x is 0.
Rate of change = 0.5
You have to use the formula of rate of change to find the answer. You can choose any pairs from the table and will give you the same answer. I pick the first pair and the last pair to find my rate of change.