(3,09:1\40-32,3:17\50)*1\4+0,069*1\3= 15.273
1) 3,9: 1/40=3ц9/10 :1/40=39/10 * 40/1=39*40 / 10*1=39*4 / 1*1=156/1=156
2) 32,3 : 17/50=32ц3/10 *50/17=323/10 * 50/17=323*50 / 10*17=19*5/1*1=95/1=95
3) 156 - 95= 61
4) 61*1/4=61/1 * 1/4= 61*1 / 1*4=61/4=15ц1/4
5) 0,069*1/3=69/1000*1/3=69*1 / 1000*3=69/1000=23/1000
6)15ц1/4 + 23/1000=61/4 + 23/1000=250*61 /250*4 + 1*23/1*1000=15250/1000 + 23/1000=15250+23 / 1000=15273/1000=15целых273/1000 = 15.273