3÷3/3,4+2/2,5×2/1,2×2/1,2-3/5,6=5(109/1260)
1) 3÷(3/3,4)=3×(3,4/3)=(3×3,4)/3=3,4=(34/10)=17/5;
2) (2/2,5)×(2/1,2)=(2÷(25/10))×(2÷(12/10))=(2÷(5/2))×(2÷(6/5))=(2×(2/5))×(2×(5/6)=(4/5)×(5/3)=(4×5)/(5×3)=4/3;
3) (4/3)×(2/1,2)=(4/3)×(2÷(12/10))=(4/3)×(2×(10/12))=(4/3)×2×(5/6)=(4×2×5)/(3×6)=(4×5)/(3×3)=20/9;
4) (3/5,6)=3÷(56/10)=3÷(28/5)=3×5/28=15/28;
5) (17/5)+(20/9)=(17×9+20×5)/45=(153+100)/45=253/45;
6) (253/45)-(15/28)=(253×28-15×45)/(45×28)=(7084-675)/1260=(6409/1260)=5(109/1260).