28.8 : 13 5/7+ 6.6: 2/3 11 2/3 : 2.25 нужно и понятно.

28,8 : 13 5/7 + 6,6 : 2/3 = 28 8/10 : 13 5/7 + 6 6/10 : 2/3 = 288/10 : 96/7 + 66/10 : 2/3 = 288/10 * 7/96 + 66/10 * 3/2 = 3/10 * 7/1 + 33/10 * 3/1 = 21/10 + 99/10 = (21+99)/10 = 120/10 = 12
11 2/3 : 2,25 = 11 2/3 : 2 25/100 = 35/33 : 225/100 = 35/33 * 100/225 = 7/33 * 100/45 = 700/1485 = 140/297