3 1/2:1 2/3+2 2/5-1 1/2:1 1/5

3 1/2 : 1 2/3 + 2 2/5 - 1 1/2 : 1 1/5 = 7/2 : 5/3 + 12/5 - 3/2: 6/5
                                                       = 7/2 x 3/5 + 12/5 - 3/2 x 5/6
                                                       = 21/10 +12/5 - 15/12
                                                       = 21* 6/10*6 + 12*12/5*12 -15*5/12*5
                                                       = 126/60 + 144/60 - 75/60
                                                       = 195/60
                                                       = 3 15/60
                                                       = 3 1/4