Question

which of these shows how to model \\(-3 - 1\\)?

subtract.

\\(-3 - 1 = \\)

Explanation:

Analyze the subtraction expression

$$ -3 - 1 $$

Evaluate the models

• The expression starts with \(-3\), represented by \(3\) negative counters (red circles with minus signs).
• To subtract \(1\) (a positive \(1\)), we need to remove \(1\) positive counter. Since there are no positive counters, we must add a zero pair (one positive green counter and one negative red counter).
• After adding the zero pair, we have \(4\) negative counters and \(1\) positive counter.
• Subtracting \(1\) means crossing out the \(1\) positive green counter.
• This matches the left model.

Determine the correct option

• Left model: Shows \(4\) negative counters and \(1\) positive counter with the positive counter crossed out. This correctly models \(-3 - 1\).
• Right model: Shows \(3\) negative counters with one crossed out, which models \(-3 - (-1)\).

Answer:

• (A) The left model (four negative counters and one positive counter with the positive counter crossed out) (Correct answer)
• (B) The right model (three negative counters with one negative counter crossed out)