4:4 4/5+2 2/7 * 5 1/4 - 7 11/12

4 : 4 4/5 + 2 2/7 * 5 1/4 - 7 11/12 = 4 11/121) 4 : 4 4/5 = 4 : 24/5 = 4 * 5/24 = 20/24 = 5/62) 2 2/7 * 5 1/4 = 16/7 * 21/4 = (4*3)/(1*1) = 123) 5/6 + 12 = 12 5/64) 12 5/6 - 7 11/12 = 12 10/12 - 7 11/12 = 11 22/12 - 7 11/12 = 4 11/12Пояснения:4 4/5 = (4*5+4)/5 = 24/52 2/7 = (2*7+2)/7 = 16/75 1/4 = (5*4+1)/4 = 21/45/6 = (5*2)/(6*2) = 10/12 - доп.множ. 2