This isn’t exactly concatenation but it will do the job you want to do:
puts " Total Revenue of East Cost: #{total_revenue_of_east_cost}"
Technically, this is interpolation. The difference is that concatenation adds to the end of a string, where as interpolation evaluates a bit of code and inserts it into the string. In this case, the insertion comes at the end of your string.
Ruby will evaluate anything between braces in a string where the opening brace is preceded by an octothorpe.