1. **State the problem:** We need to find the number of bookmarks, $n$, that must be sold for the school group to break even. This means the revenue equals the total cost. 2. **Write the given functions:** - Revenue function: $R(n) = 2n$ - Cost function: $C(n) = 144 + 0.80n$ 3. **Set up the break-even equation:** $$R(n) = C(n)$$ $$2n = 144 + 0.80n$$ 4. **Solve for $n$:** Subtract $0.80n$ from both sides: $$2n - 0.80n = 144$$ $$1.20n = 144$$ 5. **Isolate $n$ by dividing both sides by 1.20:** $$n = \frac{144}{1.20}$$ 6. **Calculate the value:** $$n = 120$$ **Answer:** The school group needs to sell **120 bookmarks** to break even.