Hey there!
To solve for the amount of beads that weigh 72 grams, you can set up this proportion where x represents the number of beads weighing 72 grams:

=

Now, cross multiply and simplify:
6*72=48*x
432=48x
Finally, solve for x:
432=48x
x=9
Therefore, 9 beads will weigh 72 grams.
Hope this helps and I hope you have a marvelous day! :)