Question

Write as an expression: a number that is equal to twice as much as x

Answer 1

Let's call the number we're looking for $y$. We know that $y$ is twice as much as $x$.

Twice as much as a number simply means the double of that number, and in turn the double of a number means to muliply that number by 2.

So, in order to obtain $y$, you have to multply $x$ by 2. In formula, you have

$y = 2\cdot x$ or simply $y = 2x$