12-3/5÷2/3
=12-3/5×3/2
=12-9/10
=11又1/10
12÷(3/5+2/3)
=12÷(9/15+10/15)
=12÷19/15
=12×15/19
=180/19
12÷[3/5×(4/3-1)]
=12÷(3/5×1/3)
=12÷1/5
=12×5
=60