Hannah brought $30 to the county fair. She spent half of it on rides and another $5 on dessert. How much, in dollars, is left? Let's be accurate as possible.

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
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She spent $30 / 2 = $15 on rides. She spent a total of $15 + $5 = $20 including dessert. She has $30 - $20 = $10 left.
The answer: 10.