We have a budget of $2000. This is the maximum cost of the reception.
The cost has a fixed part, that is $60, and a varaible part, which is $30 per person.
Then, if n is the number of people invited, then the cost can be expressed as:
[tex]C(n)=60+30\cdot n[/tex]
We know that this cost has to be $2000 at most, so we can find n as:
[tex]\begin{gathered} C(n)=60+30n\le2000 \\ 60+30n\le2000 \\ 30n\le2000-60 \\ 30n\le1940 \\ n\le\frac{1940}{30} \\ n\le64.67 \end{gathered}[/tex]
Then, as n ≤ 64.67, the maximum number of people they can invite with this budget is 64 people.
Answer: 64 people.