(6 8/15-4 21/45)*4.5-2 1/6:0,52=5 2/15
1) 6 8/15-4 21/45=98/5-201/45=294/45-201/45=93/45=31/15=2 1/5
2) 2 1/15*4.5= 2 1/15*4 5/10=31/15*45/10=279/30=93/10=9 3/10
3)2 1/6:0,52=2 1/6:52/100=13/6:52/100=13/6*100/52=50/12=4 1/6
4)9 3/10-4 1/6=93/10*25/6=279/30*125/30=154/30=77/15=5 2/15