The fraction of blue beads is 1 - 2/3 - 1/4 = 1/12
<span>If the total number of beads is t then </span> <span>red - blue = 42 </span> <span>2t/3 - t/12 = 42 </span> <span>therefore </span> <span>7t/12 = 42 </span> <span>therefore </span> <span>t = 12x42/7 = 72</span>
