15 - 13,2 : (7 2/3 - 2 1/3) = 12 целых 21/40.
1) 7 2/3 - 2 1/3 = 5 1/3
2) 13,2 : 5 1/3 = 132/10 : 16/3 = 66/5 · 3/16 = (33·3)/(5·8) = 99/40 = 2 19/40
3) 15 - 2 19/40 = 14 40/40 - 2 19/40 = 12 21/40
15 - 13,2 : (7 2/3 - 2 1/3) = 12 целых 21/40.
1) 7 2/3 - 2 1/3 = 5 1/3
2) 13,2 : 5 1/3 = 132/10 : 16/3 = 66/5 · 3/16 = (33·3)/(5·8) = 99/40 = 2 19/40
3) 15 - 2 19/40 = 14 40/40 - 2 19/40 = 12 21/40