（5/4-1/3）÷1/8+1/7
=（5/4-1/3）*8+1/7
=5/4*8-1/3*8+1/7
=10-8/3+1/7
=30/3-8/3+1/7
=22/3-1/7
=154/21-3/21
=151/21