21/6*6 (5/12+1 1/3)*3 3 3/14*7/9-2 3/14*7/9 4 4/9*5/8+5/8*3 5/9

2 1/6*6=13/6*6=13

(5/12+1 1/3)*3=(5/12+ 1 4/12)*3=1 9/12*3=1 3/4*3=7/4*3=21/4=5 1/4=5,25

3 3/14*7/9-2 3/14*7/9=7/9(3 3/14-2 3/14)=7/9*1=7/9

4 4/9*5/8+5/8*3 5/9=5/8(4 4/9+3 5/9)=5/8*8=5