1. **State the problem:** We have a small box of cereal with mass $k$ grams. 2. The jumbo box is five times as heavy as the small box. 3. We want to express the mass $m$ of the jumbo box in terms of $k$. 4. The formula relating the masses is: $$m = 5 \times k$$ 5. This means the mass of the jumbo box is five times the mass of the small box. 6. So, the expression for $m$ in terms of $k$ is: $$m = 5k$$