Answer:
(b-20)/4
Explanation:
She had b beads initially and gave 20 to his sister;
what he would have now will be;
b - 20
So he made 4 beads with the remaining
To know the number of beads on each of the four , that will be dividing the number of beads we have left by 4
Mathematically;
that will be ;
(b-20)/4