4/5+56/15+90/19-30/11-42/13-72/17=68/15+90/19-30/11-42/13-72/17=4-2-3-4+4+8/15-8/11-4/13-4/17+4/19=-1+8(1/15-1/11)+4(1/19-1/17-1/13)