2.2/7-1.3/5. 6.1/4-3.2/5. 4.1/6-1.2/3

2 2/7 - 1 3/5 = 16/7 - 8/5 = (16 *5 - 8 * 7)/35 = 80/35 - 56/35 = 24/35
6 1/4 -3 2/5 = 25/4 -17/5 =(25 * 5-17 * 4)/20=125/20 - 68/20=57/20 = 2 17/20
4 1/6  -  1 2/3 = 25/6 - 5/3 =(25 * 1 - 5* 2)/6 = 25/6 -10/6 =  15/6 = 5/2 = 2 1/2