Answer: At most 9 attendees can be there.
Explanation:
Given equation: d = 8a , where a represents the number of attendees, and the variable d represents the cost in dollars.
To find : the number of attendees, if Will budgets a total of $72 for his graduation picnic.
72=8a
⇒ 9 = a [divide both sides by 8]
∴ a= 9
Hence, at most 9 attendees can be there.