8-15分之7-五分之4除2分之3
=8-7/15-8/15
=8-1
=7
3又八分之五-13分之2除26分之9-九分之五
=3又5/8-2/13x26/9-5/9
=3又5/8-4/9-5/9
=3又5/8-1
=2又5/8
2.5X9分之1X1.25
=5/2x1/9x5/4
=25/8x/19
=25/72
【1-（4分之一+八分之三）】除4分之一
=(1-1/4-3/8)x4
=1x4-1/4x4-3/8x4
=4-1-1.5
=1.5