18 1\4-3 4\14 - x=5 1\14 + 3 13\14
(x - 7 2\17) - 4 15\17 = 5 16\17
19 1\16 - 4 8\16 - x = 6 1\16 + 3 15\16
(x + 21 3\19) - 3 18\19 = 21 17\19