Given that Oliver want to buy a deck of cards for each of his eight neices and nephews;
and each deck of cards cost d.
the total costis;
[tex]8\times d=8d[/tex]If he wants to spend less than thirty dollars, it means;
[tex]8d<30[/tex]to get the value of d, let's divide both sides by 8;
[tex]\begin{gathered} \frac{8d}{8}<\frac{30}{8} \\ d<3.75\text{ dollars} \end{gathered}[/tex]The cost of each deck could be any amount less than $3.75
[tex]d<\text{ \$}3.75[/tex]