1. The problem asks to write an equation showing when the costs of Plan A and Plan B are the same. 2. We have the expressions for the costs: Plan A: $20 + 5g$ Plan B: $10 + 7g$ 3. To find when the costs are equal, set the two expressions equal to each other: $$20 + 5g = 10 + 7g$$ 4. Now solve for $g$ step-by-step: Subtract $5g$ from both sides: $$20 + \cancel{5g} = 10 + 7g - \cancel{5g}$$ which simplifies to $$20 = 10 + 2g$$ 5. Subtract 10 from both sides: $$20 - 10 = 10 - 10 + 2g$$ which simplifies to $$10 = 2g$$ 6. Divide both sides by 2: $$\frac{10}{\cancel{2}} = \frac{2g}{\cancel{2}}$$ which simplifies to $$5 = g$$ 7. So, the two plans cost the same when $g = 5$. 8. The equation showing when the two plans cost the same is: $$20 + 5g = 10 + 7g$$