1. **State the problem:** Tanisha has a cell phone plan with a base charge of 25 per month that includes 500 international minutes. For every minute over 500, she pays 2 per extra minute. We need to find the total cost if she uses 23 minutes over the limit and also express the total cost if she goes over by $x$ minutes. 2. **Formula:** The total cost $C$ when going over by $x$ minutes is given by: $$C = 25 + 2x$$ where 25 is the base charge and $2x$ is the cost for the extra minutes. 3. **Calculate cost for 23 extra minutes:** $$C = 25 + 2 \times 23$$ $$C = 25 + 46$$ $$C = 71$$ 4. **Express cost for $x$ extra minutes:** $$C = 25 + 2x$$ 5. **Explanation:** The base charge is fixed at 25 regardless of usage up to 500 minutes. For every minute beyond 500, an additional 2 is charged. So, the total cost increases linearly with the number of extra minutes. **Final answers:** - Total cost when over by 23 minutes: $71$ - Total cost when over by $x$ minutes: $25 + 2x$