(-1/42)/(1/6-2/7)+2/3+3/14=(-1/42)/(7/42-6*2/42)+2/3+3/14=(-1/42)/(-5/42)+2/3+3/14=1/5+2/3+3/14=3/15+2*5/15+3/14=13/15+3/14=(13*14+3*15)/(15*14)=227/210