A cup of coffee has cooled from 98degreesC to 50degreesC after 15 minutes in a room at 25degreesC. How long will it take to cool to 40degrees​C?

Someone else helped me on a problem similar to this, however I keep getting it wrong by decimals. i.e the answer is 35.987 but i put in 35.867
I can't imagine why I'm getting it wrong, ive checked and double checked my formulas over and over
Thank you

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  2. Too bad you didn't show your work...

    25+(98-25)e^(-15k) = 50
    k = 0.0714

    So, to find t when T=40,
    25+73e^(-0.0714t) = 40

    Is this what you did?
    If not, what did you do?

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