Find the 3 trig values of the given angle. No calculator! 1. 7π/3

I don't really care about the answer as I have it can someone just explain how to get reference angle?

Hart manufacturing had six-month sales of $80 million, with $20 million of that amount from the internet. it set a goal to increase the percentage of total sales coming from the internet by 4 percent in the next six months. the results were total sales of $85 million. if the company meets its goal exactly, what will the dollar amount of internet sales be?