1/4 + ((1 1/2 + 2 2/3) : 3 3/4 - 2/3) : 8 8/9 = 1/4 + ((3/2 + 8/3) : 15/4 - 2/3) : 80/9 = 1/4 + ((9+16)/6 : 15/4 - 2/3) : 80/9 = 1/4 + (25/6 * 4/15 - 2/3) : 80/9 = 1/4 + (10/9 - 2/3) : 80/9 = 1/4 + (10-6)/9 : 80/9 = 1/4 + 4/9 * 9/80 = 1/4 + 1/20 = (5+1)/20 = 6/20 = 3/10 = 0,3