18/19-7/19+3/19 = 14/19
9/11-3/11-2/11 = 4/11
11/15-(3/15+7/15) = 1/15
18/19-7/19+3/19=7/19+3/19=10/19=18/19-10/19=8/19
9/11-3/11-2/11=9/11-3/11=6/11-2/11=4/11
11/15-(3/15+7/15)=3/15+7/15=10/15=11/15-10/15=1/15
18/19-7/19+3/19 = 14/19
9/11-3/11-2/11 = 4/11
11/15-(3/15+7/15) = 1/15
18/19-7/19+3/19=7/19+3/19=10/19=18/19-10/19=8/19
9/11-3/11-2/11=9/11-3/11=6/11-2/11=4/11
11/15-(3/15+7/15)=3/15+7/15=10/15=11/15-10/15=1/15