1) 3.09: 1/40=309/100:1/40 =309/100*40/1=618/5

2)32,3:17/50=323/100*50/17= 19/2

3)618/5 - 19/2= 1236/10 -95/10= 1141/10

4)1141/10*1/4= 1141/40=28,525

5)69/1000*1/3=23/1000=0,023

6)28,525+0,023=28,548