If 60% of (x - y) = 45% (x + y) and y = k% of x, then 21% of k is equal to:

1 6 7 3

3

60% = \(\frac{3}{5}\) , 45% = \(\frac{9}{20}\) (x – y) ×  \(\frac{3}{5}\) = (x + y) × \(\frac{9}{20}\)  (x – y) × 4 = (x + y) × 3 4x - 4y = 3x + 3y \(\frac{x}{y}\) = \(\frac{7}{1}\) Nw ,  y = k% of x  1 = k% × 7  k% = \(\frac{1}{7}\) k  = \(\frac{100}{7}\)  21% of k  = \(\frac{21}{100}\)  ×\(\frac{1}{7}\)  k =3