These two rectangles are similar. Find the missing dimension. (I need an answer ASAP, I also need a step by step answer because this is a study guide and I need to study for my upcoming math test).

Answer:
X=8
Step-by-step explanation:
If you divide 5 by 2 you get 2.5. To figure out X, all you have to do is divide 20 by 2.5 as well, which gets 8. Since they are similar, this can work.