title: Twig math with variables
body: <p>I want to do some math in twig. I've got 2 variables, price and quantity and i want to multiply them. But when I do it like this: </p>
  
  <pre><code>{{ {{ carts.price }} * {{ carts.quantity }} }}
  </code></pre>
  
  <p>It returns an error</p>
  
  <pre><code>A hash key must be a quoted string, a number, a name, or an expression enclosed in parentheses (unexpected token "punctuation" of value "{".
  </code></pre>
  
  <p>How can i do this </p>