Let x be the total number of beads.
Red beads: 2/3x
Pink beads: 1/4x
White beads: x-2/3x-1/4x = 12/12x-8/12x-3/12x = 1/12x
Using the 28 more, you get the equation
Red -28 = White
Substituting x for each, you get:
2/3x - 28 = 1/12x
8/12x - 28 = 1/12x
7/12x = 28
1/12x = 4
x = 48 beads in total