[6又3/5 -(8.5-1/3)÷3.5]×(2又5/18+11/12)
= [33/5 -(17/2-1/3)×2/7]×(41/18+11/12)
= [33/5 -49/6×2/7]×115/36
= [33/5-7/3]×115/36
= 64/15 ×115/36
= 736/39