Respuesta :

chaparrahdz77
Formula for are of a rectangle:
        A =L * W
1st isolate W
   147 = 3W * W
   147 = 3W^2
divide 147 by the by 3 on bot sides
    29 = W^2
get ride of the square by square rooting on both sides
     7 = W

2nd find the perimeter
    P = 2(7) + 2(21)
    P = 14 + 42
    P = 56