To find out how many classes Jill must teach for her income to match her expenses, we can set up the equation based on her total expenses and income per class.
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Calculate total expenses:
- Instruments cost: $525
- Facility charge per class: $40
- Instructor payment per class: $65
Therefore, the total expense per class is: \[ \text{Total Expense per Class} = \text{Facility Charge} + \text{Instructor Payment} \] \[ \text{Total Expense per Class} = 40 + 65 = 105 \]
Thus, if she teaches \( x \) classes, her total expenses for \( x \) classes will be: \[ \text{Total Expenses} = 525 + 105x \]
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Calculate total income:
- She earns $65 per class, so for \( x \) classes: \[ \text{Total Income} = 65x \]
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Set the total income equal to total expenses: \[ 65x = 525 + 105x \]
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Rearranging the equation: \[ 65x - 105x = 525 \] \[ -40x = 525 \] \[ x = \frac{525}{40} \] \[ x = 13.125 \]
Since Jill cannot teach a fraction of a class, she needs to round up. Therefore, Jill needs to teach 14 classes to ensure her income exceeds her expenses.
Thus, the final answer is: \[ \boxed{14} \]