5 x 10 12 1 2 x 9 1 2 July 8, 2019 16 32 64 128 5 x 10 12 1 2 x 9 1 2 envelope Usps produced envelope 10 x 5 or 12 1 2 x 9 1 2 5 5 - x = 12 9 5 + 9 = 14 5/12 x 9
