Please answer the following question by reasoning step-by-step.
Mathilda is determined to pay back the money she owes a friend so she decides to pay an initial installment of $125. If she still has 75% left to pay, how much did she owe originally?

500
Percentage means per 100, so if she still owes 75%, she must have paid 100% - 75% = 25% of the original amount.

25% of the original amount = (25 / 100) * original amount = $125.

Multiplying both sides by (100 / 25) gives: original amount = (100 / 25) * $125 = $500.

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The answer: 500