[tex] \bf A)
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\cfrac{3\left( \frac{2y}{a} \right)}{y}\implies \cfrac{\frac{6y}{a}}{y}\implies \cfrac{6y}{a}\cdot \cfrac{1}{y}\implies \cfrac{6}{a}\quad \otimes
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B)
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\cfrac{6\left( \frac{2y}{a} \right)}{y}\implies\cfrac{\frac{12y}{a}}{y}\implies \cfrac{12y}{a}\cdot \cfrac{1}{y}\implies \cfrac{12}{a}\quad \otimes
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C)
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\cfrac{6y}{\left( \frac{2y}{a} \right)}\implies \cfrac{6y}{1}\cdot \cfrac{a}{2y}\implies 3a\quad \otimes [/tex]
[tex] \bf D)
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\cfrac{12\left( \frac{2y}{a} \right)}{y}\implies \cfrac{\frac{24y}{a}}{y}\implies \cfrac{24y}{a}\cdot \cfrac{1}{y}\implies \cfrac{24}{a}\quad \otimes
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E)
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\cfrac{12y}{\left( \frac{2y}{a} \right)}\implies \cfrac{12y}{1}\cdot \cfrac{a}{2y}\implies 6a\quad \checkmark [/tex]