原式=[-14/5*(14/5*10/7)^3*(-5/12)*(-5/12)*(-3/20)]/(-1/6+1/12-1/20-1/30)
=(14/5*5/12*4^3*1/4^2)/(-1/2+1/3+1/3-1/4-1/4+1/5-1/5+1/6)
=(14*4/12)/(-1+5/6)
=(14/3)/(-1/6)
=-28