[tex] \frac{5}{7} \: \: \: of \: \: \: x = \frac{5}{21} \\ = > \frac{5x}{7} = \frac{5}{21} \\ = > 5x = \frac{5}{21} \times 7 \\ = > 5x = \frac{5}{3} \\ = > x = \frac{5}{3} \times \frac{1}{5} \\ = > x = \frac{1}{3} [/tex]
Answer:
[tex]x = \frac{1}{3} [/tex]
Hope you could get an idea from here.
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