(1 17/25 * 2 1/7 - 2 4/7 * 1 2/5 ) * 2 7/9=
= ( 42/25 * 15/7 - 18/7 * 7/5 ) * 25/9 =
= ( 18/5 - 18/5 ) * 25/9 = 0
по действиям:
1) 1 17/25 * 2 1/7 = 42/25 * 15/7 = (6*3)/(5*1) =18/5= 3 3/5
2) 2 4/7 * 1 2/5 = 18/7 * 7/5 = 18/5 = 3 3/5
3) 3 3/5 - 3 3/5 = 0
4) 0 * 2 7/9 = 0