1/4 + 5/17 - 2 1/15 - 2 1/8 - 51/56 = 1/4 + 5/17 - 31/15 - 17/8 - 51/56
= (1/4 - 17/8) + (5/17 - 51/56) - 31/15
= -15/8 + (195 - 867)/952 - 31/15 = -15/8 - 672/952 - 31/15 = -15/8 - 21/30 - 31/15 = -15/8 - 7/10 - 31/15 = -56.25 - 0.7 - 2.066... = -59.016...