((4 2/3 - 5/9 * 2 4/7)/( 2 1/7 + 1 2/3):5) :0.8*1.25 = 5 1/4
1) 5/9 * 2 4/7 = 5/9 * 18/7 = 10/7 ( 18 и 9 сокращаются)
2)4 2/3 - 10/7 = 14/3 - 10/7 = 68/21 ( приводим к общему знаменателю)
3)2 1/7 + 1 2/3 = 15/7 + 5/3 = 80/21
4)80/21 : 5 = 80/21 * 1/5 = 80/105 = 16/21
5) 68/21 : 16/21 = 68/21 * 21/16=68/16 = 34/8=17/4
6)0.8*1.25 = 1
7) 17/4 + 1 = 21/4 = 5 1/4