2 5x 15 7 July 8, 2019 16 32 64 128 2 5x 20 )-( 15 8x )= 7 2 5x 3 10x 4 15 7 20x 1 4 2 5x 15 7x 12 2 5x 2 7x 15 25x 2 70x 15 5x 2 15 x 7 6 5x 2 6 7x )= 15 5x 2 41x 15 ≤ 7 2 15 3 5x 7 15 2 3x 2 2x 15 5x =- 2 7x 14