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The perimeter P of a rectangle is given by the formula,

P = 2L + 2W = 2 (L + W)

Where L is the length and is W is the width of the rectangle.

The perimeter P of a rectangle is

P = 2 (7 m + 12 m)                (Substitute L =12 m and W =7 m)

  = 2 X 19 m                            (Add 7 + 12 = 19)

  = 38 m                                  (Multiply 2 X 19 = 39)

Perimeter is 38 m