How can an expression written in either radical form or rational exponent form be written to fit the other form?

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The number if marbles of different colors stored in a hat is listed below: 4 red marbles 10 green marbles 7 blue marbles. without looking in the hat, dan takes out a marble at random. he replaces the marble and then takes out another marble from the hat. what is the probability that dan takes out a blue marble in both draws?

Write the rational number in lowest terms 99/-15