How do I calculate percents?

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Okay so I never really learned percentages and I need to know how much a game will be after I have used a coupon. The game is $9.99 and the coupon is 75% off. How do I calculate the new price of the game? Please explain how you did it so I don't have to ask another embarrassing question like this again. Thanks!

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@Essam A - I didn't ask for your opinion. I asked for an answer. Grow up

How do I calculate percents?