Xavier, Yvonne, and Zelda each try independently to solve a problem. If their individual probabilities for success are $$\frac{1}{4}$$, $$\frac{1}{2}$$ and $$\frac{5}{8}$$ respectively, what is the probability that Xavier and Yvonne, but not Zelda, will solve the problem?
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A$$\frac{11}{8}$$
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B$$\frac{7}{8}$$
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C$$\frac{9}{64}$$
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D$$\frac{5}{64}$$
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E$$\frac{3}{64}$$