X 5 12x 1 4 July 8, 2019 16 32 64 128 4x 1 18x x 5 12x 5 x 4 1 12x 21 X − 7 − 42x 5 12x 1 X 2 3 =- 1 12x 4 5 X 4x 1 6x 5 12x 31