Putting text after inputting a variable

How would I have text after a variable is entered so for example: I need to put a comma after the first number.. so it'd say 5, 5 instead of 55.

Code:

cout << "The slope of every horizontal line is " << slope(Need a comma here) << slope2 << '\n';

This what you are asking?

Code:

cout << "The slope of every horizontal line is " << slope << ", " << slope2 << '\n';

Yes, thanks.