7/18+1/9=9/18=1/2=0.5
1/2-3/8=1/8=0.125
1/21-9/14=2-27/42= -25/42
5/42-8/21=5-16/42= -11/42
13/24:26/33=13/24*33/26=11/16
7/15-(2/3*5/6)=7/15-5/9= -4/45
7/18+1/9=9/18=1/2=0.5
1/2-3/8=1/8=0.125
1/21-9/14=2-27/42= -25/42
5/42-8/21=5-16/42= -11/42
13/24:26/33=13/24*33/26=11/16
7/15-(2/3*5/6)=7/15-5/9= -4/45