(3,9 - 2,55+4 5/12-1 1/15):4,7. Это первая строка (0,81*8 1/3 - 0,57:4 3/4):2,21+4,125:2 1/16 Вторая строка

а) (390/100 - 255/100 + (4 * 12 + 5)/12 - (1 * 15 + 1)/15) * 10/47 = (27/20 + 53/12 - 16/15) * 10/47 = (81/60 + 265/60 - 64/60) * 10/47 = (81 + 265 - 64)/60 * 10/47 = 282/(6 * 47) = 1;б) (81/100 * (8 * 3 + 1)/3 - 57/100 : (4 * 4 + 3)/4) * 100/221 + 4125/1000 : (2 * 16 + 1)/16 = (81/100 * 25/3 - 57/100 * 4/19) * 100/221 + 33/8 * 16/33 = (675/100 - 12/100) * 100/221 + 2 = 663/100 * 100/221 + 2 = 3 + 2 = 5.