To find domain:
 ⇒ must define what is a domain
 ⇒ Domain is the set of input values or the values of the x-axis of 
 graph that is covered by the function
Based on the definition:
 ⇒ 67 ≤ x ≤ 78 is the domain of the function
Answer: 67 ≤ x ≤ 78 where x is a whole number
Hope that helps!