|- 5/18| + | - 1/6 |=5/18+1/6=8/18=4/9
|- 5/18| + | - 1/6 | = |-5/18 | + |-3/18| = 5/18 + 3/18 = 8/18.
|- 5/18| + | - 1/6 |=5/18+1/6=8/18=4/9
|- 5/18| + | - 1/6 | = |-5/18 | + |-3/18| = 5/18 + 3/18 = 8/18.