Mai has picked one cup of strawberries for cake, which is enough for 3/4 of the cake. how many cups does she need for the whole cake?

answer:  

\boxed {\frac{1}{5}}  

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solution-

60 *   \frac{1}{5}   = 12

90 * \frac{1}{5} = 18

75 * \frac{1}{5} = 15

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hence, the answer would be \boxed {\frac{1}{5}}