Final answer:
Rhea's savings increased by $10,000 over the five-year period.
Step-by-step explanation:
In this situation, the initial amount of money Rhea put into savings was $20,000, and now it is worth $30,000. To find the increase in value, we can subtract the initial amount from the final amount: $30,000 - $20,000 = $10,000. This means that Rhea's savings increased by $10,000 over the five-year period.