Can someone help me with geometry

Cameron indoor stadium at duke university is one of the most revered sites in all of college basketball, as well as in all of sports period. duke’s men’s and women’s basketball programs have attained quite a few wins in the building over the last seventy years. cameron indoor stadium is capable of seating 9,460 people. for each game, the amount of money that the duke blue devils’ athletic program brings in as revenue is a function of the number of people in attendance. if each ticket costs $45.50, find the domain and range of this function.

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

Another type of subtraction equation is 16-b=7. explain how you would sole this equation then solve it.