3 6 21 5 8 July 8, 2019 16 32 64 128 9x 5 (- 8x 3 )- 6 =- 21 2 5 12 and 3 6 21 and 8 11 3 2x 5 6 5 8x 17 21 9x 5 (- 8 3 )- 6 =- 21 3 7 6 11 8 by 21 5 22
