Respuesta :

So first of all we need to know that area is length times width
Area = L x W 
since we know the area is 42 and the length is 12 lets plug those in
42 = 12 x W 
now we dont know what W is yet but we can figure it out by dividing 42 by 12
42/12 = 3.5 
So W = 3.5!
but its asking for the perimeter and we know that perimeter is all of the sides of the rectangle added up. Heres a picture
   
       ___3.5___
      |                 |
      |                 |
 12 |                 |  12 
      |                 |
      ************
             3.5

see now we just add those all up together:)

12 + 12 + 3.5 + 3.5 = 31!!
so our perimeter is 31 inches:)
have a good one 
PICK ME BRAINLIEST!:D