1) 2 5/12 * 2 = 29/12 * 2 = 29/6 = 4 5/6
2) 4 5/6 - 5 4/45 = 4 75/90 - 5 8/90 = -( 4 98/90 - 4 75/90)= -23/90
3) -23/90 + 0,2 = -23/90 + 2/10 = -23/90 + 18/90 = -5/90 = -1/18
4) -1/18 : 0,75 = -1/18 * 4/3 = -2/27
5) -2/27 + 0,25 = -2/27 + 1/4 = -8/108 + 27/108 = 19/108
ответ: 19/108