Aryana, this is easier than it seems, I promise!
Let's let s = his normal salary. For the first 40 hours, he makes 40s, right?
Since he worked 9 extra hours and got paid double, then his salary for that is 9(2s) = 18s.
We add the two together for his total salary.
40s + 18s =580
58s = 580
s = 10
So his normal salary is $10/hour.
Hope this helps!