7/10*{1/24+3/14*2+（19/12-5/8）}
=7/10*(1/24+3/7+19/12-5/8)
=7/10*(1/24+3/7+38/24-15/24)
=7/10*[(1+38-15)/24+3/7]
=7/10*(1+3/7)
=7/10*10/7
=1