1. **State the problem:** Elif's integer chip model shows the subtraction equation $4 - 5 = ?$ using positive and negative chips. 2. **Understand the chips:** - Each positive chip represents $+1$. - Each negative chip represents $-1$. - Crossing out chips means removing them (subtracting). 3. **Model the subtraction:** - Start with 4 positive chips (since the problem is $4 - 5$). - Subtract 5 positive chips (crossed out). 4. **Calculate step-by-step:** - Initially, $4$ positive chips represent $+4$. - Subtracting $5$ positive chips means removing $5$ from $4$. 5. **Use integer subtraction rule:** $$4 - 5 = 4 + (-5)$$ 6. **Add the integers:** $$4 + (-5) = -1$$ 7. **Final answer:** $$4 - 5 = -1$$ Elif's subtraction equation is complete: $4 - 5 = -1$.