Final answer:
The international texting plan is more cost-effective for sending 500 text messages in a month.
Step-by-step explanation:
To determine which plan is more cost-effective for sending 500 text messages in a month, we need to compare the costs of the two plans. The international texting plan charges $45 for 300 text messages included. For the remaining 200 messages, at a cost of $0.10 per message, the additional cost would be $20. The total cost for the international texting plan for 500 messages would be $45 + $20 = $65.
On the other hand, the unlimited plan charges a flat fee of $59 per month, regardless of the number of messages sent.
Therefore, the international texting plan is more cost-effective for sending 500 text messages in a month as it costs $65 compared to the $59 charge of the unlimited plan.