1又1/3×[21÷（4又1/12 - 2.625）-4又1/2]÷3又3/5
=1又1/3×[21÷（4又1/12 - 2又5/8）-4又1/2]÷3又3/5
=1又1/3×[21÷35/24-4又1/2]÷3又3/5
=1又1/3×[14.4-4又1/2]÷3又3/5
=4/3×9.9÷18/5
=13.2×5/18
=11/3
=3又2/3