1)1 1/2 -8/45= 1*2+1/2 - 8/45= 3/2 - 8/45= 45*3/45*2 - 2/8/2*45= 135/90 - 16/90= 135-16/90= 119/90= 1 29/90
2)2 7/90 - 1 29/90= 2*90+7/90 - 1*90+29/90= 187/90 - 119/90= 187-119/90= 68/90= 34*2/45*2= 34/45
3)2 7/15 - 1 1/12= 2*15+7/15 - 1*12+1/12= 37/15 - 13/12= 4*37/4*15 - 5*13/5*12= 148/60 - 65/60= 148-65/60 = 83/60= 1 23/60
4)1 23/60 + 34/45= 1*60+23/60 + 34/45= 83/60 + 34/45= 3*83/3*60 + 4*34/4*45= 249/180 + 136/180= 385/180= 77*5/36*5= 77/36= 2 5/36