(2 4/5+1 2/3)*15 = (14/5+5/3)*15 = (42+25)/15*15 = 67/15*15/1 = 67
(3 3/4+9 1/6)*1 1/5 = (15/4+55/6)*6/5 = (45+110)/12*6/5 = 155/12*6/5 = 31/2 = 15 1/2
15*4/15-(10 1/2*2/3)*3/14 = 15*4/15-(21/2*2/3)*3/14 = 4-7*3/14 = 4-3/2 = (8-3)/2 = 5/2 = 2 1/2
4 2/3+7/15*1 11/14-1 1/5 = 14/3+7/15*25/14-6/5 = 14/3+5/6-6/5 = (140+25-36)/30 = 129/30 = 4 9/30 = 4 3/10