Answer
$\color{blue}{2(x+y)}$
Work Step by Step
The expression "sum of two numbers" means the operation involved is addition.
Thus, if we let the numbers be $x$ and $y$, then "the sum of two numbers" means $x+y$.
The expression "twice" means the operation involved is multiplication, and the number to be multiplied is $2$.
Therefore, "Twice the sum of two numbers" means:
$\color{blue}{2(x+y)}$