marcus wants to use a model to determine the difference − 8 − 3 ( + 3 ) -8-3+3. he starts with 8 negative counters. he wants to add 3 positive counters to the model without changing the value. how can he do that?

a. add 3 positive counters

b. add 3 positive counters and take away 3 negative counters

c. add 3 negative counters

d. add 3 positive counters and 3 negative counters