2) 2) к числу 1 5/6 прибавить сумму чисел -3 1/4 и 2 2/5;

(1 + 5/6) + ((-3 - 1/4) + (2 + 2/5)) = (1 + 5/6) + (-3 + 2 - 1/4 + 2/5) = (1 + 5/6) + (-1 + -1/4 + 2/5) = (1 + 5/6) + (-1 - 5/20 + 8/20) = (1 + 5/6) + (-1 + 3/20) = 1 + 5/6 - 1 + 3/20 = 5/6 + 3/20 = 50/60 + 9/60 = 59/60 = 0.9833