（-2/5)除以（-5又1/4）x（-4又3/8)
=-2/5÷21/4×35/8
=-2/5×4/21×35/8
=-1/3
(-4)³÷（-2/3)² -6
=-64÷4/9-6
=-64×9/4-6
=-114-6
=-120
2-(-12)除以(-2/3) -3
=2-12×3/2-3
=2-18-3
=-19
2-(-6)2除以（-2/3)
=2+36÷2/3
=2+36×3/2
=58