we know there are 260 handouts, and he's making packets of 64 each, and 4 leftover, if the packets are say "x", then the amount of handout total for the packets alone is 64 * x, or 64x, and if we add the leftover 4, that'd be the total of handouts of 260.
[tex]\bf \stackrel{\textit{packets of 64 handouts each}}{64x}+\stackrel{\textit{leftover}}{4}~~=~~\stackrel{\textit{total}}{260}[/tex]
