<em>Your question has confusing details. So, I will rephrase as:</em>
<em>How many 2' x 4' would be needed for Bottom Plates and Double Top Plates on a Building 25' x 50' ?
</em>
<em></em>
Answer:
12.5 plates
Step-by-step explanation:
Given
Building dimension:


Plates


To do this, we have to divide the dimension of the building by the dimension of the plates
So, we have:

and

For the length, we have:


For the width, we have:


So, 12.5 of the plates are needed