A box contained black beads and white beads. At first, the number of black beads was \(\frac{1}{3}\) the number of white beads. After \(\frac{1}{4}\) of the black beads and \(\frac{3}{8}\) of the white beads were used, 63 beads were left.

(a) What fraction of the beads were used?

(b) How many beads were there in the box at first?