How to use nested logical If() function to show a relevant category value in a column ?

Content

I have a scenario where I have 3 categories. (Basic, Economy,Luxury) 
If the value of a column is less than 25 its basic. If value is less than 60, its economy and last one will be premium like wise. 

However , by using this if() function we can only evaluate Yes or No. What if we have 3 categories to show.Example mentioned above. I can handle 2 categories using this if() function but what if I have to show 3 categories. 

Looking forward for an answer. 
Thanks

Version

OSvC 18B

Code Snippet

             if(sum(to_number(incidents.c$job_revenue)) /contacts.C$Total_Revenue*100 > 60, 'Premium','Economy')