8/15+5/12-3/15-1/12
=(8/15-3/15)+(5/12-1/12)
=5/15+4/12
=1/3+1/3
=2/3
2/5+2/3-（1/5+1/3）
=2/5-1/5+(2/3-1/3)
=1/5+1/3
=3/15+5/15
=8/15
设正方体边长为x
4*x*x=60
x*x=15
6*x*x=6*15=90
设正方体边长为x
4.5x*4=7.2
x=0.4
0.4*4.5*0.4=0.62
8/15+5/12-3/15-1/12
=(8/15-3/15)+(5/12-1/12)
=5/15+4/12
=1/3+1/3
=2/3
2/5+2/3-（1/5+1/3）
=2/5-1/5+(2/3-1/3)
=1/5+1/3
=3/15+5/15
=8/15
设正方体边长为x
4*x*x=60
x*x=15
6*x*x=6*15=90
设正方体边长为x
4.5x*4=7.2
x=0.4
0.4*4.5*0.4=0.62