23 3/7 = 164/7
0.9 * 2/3 x = 1.8/3 x = 0.6x
4/7*(4.2x - 4.25) = 4/7 * 4.2x - 4*4.25/7 = 4*0.6x - 17/7 = 2.4x - 17/7
4/7*(4.2x - 4.25) + 0.9 * 2/3 x + 23 3/7 = 2.4x - 17/7 + 0.6x + 164/7 = 3x + 147/7 = 3x + 21
