(3 7/15 * 0.25 + 5/6 - 1 2/5) : (5.4 : (3/20 + 0.75)
1)3 7/15 * 0.25 = 3 7/15 * 1/4 = 52/15 * 1/4 = 13/15
2)13/15 + 5/6 =26/30 + 25/30 = 51/30
3)51/30 - 1 2/5 = 51/30 - 7/5 = 51/30 - 42/30 = 9/30
4)3/20 + 0.75 = 3/20 + 3/4 = 3/20 + 15/20 = 18/20
5)5.4 : 18/20 = 5 2/5 : 18/20 = 27/5 : 18/20 = 27/5 * 20/18 = 108/18 = 6
6)9/30 : 6 = 9/30 : 180/30 = 9/30 * 30/180 = 1/20
Ответ : 1/20