=（85+1/3）×3/8+（71+1/6）×6/7+（56+1/4）×4/5
=（80+5又1/3）×3/8+（70+1又1/6）×6/7+（50+6又1/4）×4/5
=（80+16/3）×3/8+（70+7/6）×6/7+（50+25/4）×4/5
=80×3/8+16/3×3/8+70×6/7+7/6×6/7+50×4/5+25/4×4/5
=30+2+60+1+40+5
=138