А) 7/36 + 1/5 + 5/36 = 1/5 + (7/36 + 5/36) = 1/5 + 12/36 = 1/5 + 1/3 = 3/15 + 5/15 = 8/15
б) 19/42 - (5/42 + 1/5) = 19/42 - 5/42 - 1/5 = 14/42 - 1/5 = 1/3 - 1/5 = 5/15 - 3/15 = 2/15
в) (1/6 + 7/15) - 2/15 = 1/6 + (7/15 - 2/15) = 1/6 + 5/15 = 1/6 + 1/3 = 1/6 + 2/6 = 3/6 = 1/2
г) 7/18 - 0,2 + 1/9 = (7/18 + 1/9) - 0,2 = (7/18 + 2/18) - 0,2 = 9/18 - 0,2 = 1/2 - 0,2 = 0,5 - 0,2 = 0,3
д) 8/25 + 7/20 - 0,45 = (8/25 + 7/20) - 0,47 = (32/100 + 35/100) - 0,47 = 67/100 - 0,47 = 0,67 - 0,47 = 0,2