{7/3+（5.4-x）*5/3}/31/4=2 7/3+（5.4-x）*5/3=8/31 7+（5.4-x）*5=24/31 7/5+（5.4-x）=24/155 7/5+27/5-x=24/155 x=7/5+27/5-24/155 x=1030/155=206/31约等于6.65