Tìm x

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j) \( 3 \left( x - \sqrt{\frac{1}{16}} \right) - \sqrt{9} = \sqrt{49} \)

k) \( 3 \left( x - \sqrt{\frac{4}{9}} \right) = \sqrt{\frac{81}{4}} \)

l) \( 5 \left( \sqrt{\frac{1}{25}} - x \right) - \sqrt{\frac{1}{81}} = -\frac{1}{9} \)