18/11-(7/11+3/8) = 0.625
18/11-(7/11+3/8)=18/11-7/11-3/8=1-3/8=5/8
18/11-7/11-3/85/8
18/11-(7/11+3/8)=18/11-7/11-3/8=(18/11-7/11)-3/8=11/11-3/8=8/8-3/8=5/8