$\frac{48 * 35 + 20}{45 * 37 + 35} - \frac{731 : 17 + 2109 : 37}{3942 : 54 + 1755 : 65} = \frac{(4 * 12) * (5 * 7) + 20}{(5 * 9) * 37 + 5 * 7} - \frac{43 + 57}{73 + 27} = \frac{(4 * 5) * (12 * 7) + 20}{5 * (9 * 37 + 7)} - \frac{100}{100} = \frac{20 * 84 + 20}{5 * (333 + 7)} - 1 = \frac{20 * (84 + 1)}{5 * (333 + 7)} - 1 = \frac{20 * 85}{5 * 340} - 1 = \frac{20 * 5 * 17}{5 * 20 * 17} - 1 = \frac{20 * 5 * 17}{5 * 20 * 17} - 1 = 1 - 1 = 0$

$\frac{53 * 35 - 221}{646 : 17} - \frac{46 * 64 - 1306}{702 : 18} + \frac{16807 : 7}{343 * 7} = \frac{1855 - 221}{38} - \frac{2944 - 1306}{39} + \frac{2401}{2401} = \frac{1634}{38} - \frac{1638}{39} + 1 = \frac{1634}{38} - \frac{1638}{39} + 1 = 43 - 42 + 1 = 1 + 1 = 2$