# If a problem says one number is twice as large as another, which number should I choose as my variable?

Lets say that the first number is a $3$, then the second number would be $3 \cdot 2 = 6$ .
If you decided to use variable we would say that $x = 3$ so $x \cdot 2 = 6$.
So your expressions would be $x$ and $2 x$.