# JavaScript (ES6), 40 bytes

Expects an array of 12 prices.

<!-- language-all: lang-javascript -->

    a=>a.reduce((t,v,i)=>t+v*(m+=6-i)*2,m=0)

[Try it online!][TIO-kwp9abdl]

[JavaScript (Node.js)]: https://nodejs.org
[TIO-kwp9abdl]: https://tio.run/##NYlNDoMgGAWv4hIUv/BTkC7wIk0XBLGxUTFKuT4lJd28yZt522Qvdy5H7Pcw@TybbM1o4fTTx3mEIklkwWaMXWrR1hnVL7jlZDMUZxf2K6we1vBCM3rwASQlDZdAC@oO9AdV3z/Ram/AZZH6DqpQMA1ckYaVqkUlE0@M8xc "JavaScript (Node.js) – Try It Online"