M-Language: Beginner Question

I am an absolute newbie to M, and I am currently playing around with simple code snippets to understand the syntax of the language. Below is my code. I have 3 input variables (product price, qantity sold and product name) and I want to output all three of them (multiply product price with qantity and display the product name). 

let
    blue_shirt_price = 25,
    blue_shirt_qty_sold = 10,
    product_name = "Blue Shirt"

in
    blue_shirt_price * blue_shirt_qty_sold & product_name

This is the error message I am getting:

An error occurred in the ‘’ query. Expression.Error: We cannot apply operator & to types Number and Text.
Details:
    Operator=&
    Left=250
    Right=Blue Shirt

I couldn't figure out how to properly add my string variable to the IN block.

Any help is highly appreciated. Thanks!