Find the average rate of change

Need ! the total ticket sales for a high school basketball game were $2,260. the ticket price for students were $2.25 less than the adult ticket price. the number of adult tickets sold was 230, and the number of student tickets sold was 180. what was the price of an adult ticket?

Extra points! find the missing dimension! need asap

Rationalize the denominator- 12x/√x-10