More on generic Scala functions

Trying to implement, in Scala, the following Haskell function (from Learn You a Haskell...) so that it works with Int, Double, etc.

doubleUs x y = x * 2 + y * 2 

Note that this is similar to Scala: How to define "generic" function parameters?

Here's my attempt and error. Can someone explain what's happening and offer a solution. Thanks.

scala> def doubleUs[A](x:A,y:A)(implicit numeric: Numeric[A]): A = numeric.plus(numeric.times(x,2),numeric.times(y,2)) 
<console>:34: error: type mismatch;
 found   : Int(2)
 required: A
       def doubleUs[A](x:A,y:A)(implicit numeric: Numeric[A]): A = numeric.plus(numeric.times(x,2),numeric.times(y,2))