4.8x（5/6+5/8-5/12)
=4.8x5/6+4.8x5/8-4.8x5/12
=4+3-2
=5
4/15-0.64+13/5-0.36
=(4/15+13/5)-(0.64+0.36)
=(4/15+39/15)-1
=43/15-1
=28/15