Решите по действиям 1 2/3 - 5/14 + ( 1 3/4 - 1/12 ) - 4/21= ?

1) 1 3/4 - 1/12 = 7/4 - 1/12 = 21/12 - 1/12 = 20/12 = 1 8/12 = 1 2/3
2) 1 2/3 - 5/14 = 5/3 - 5/14 = 70/42 - 15/42 = 55/42 = 1 13/42
3) 1 13/42 + 1 2/3 = 55/42 + 20/12 = 110/84 + 140/84 = 250/84 = 125/42
4) 125/42 - 4/21 = 125/42 - 8/42 = 117/42 = 2 33/42