-1.5+2.25-2分之1-4分之1
=-1.5+2.25-0.5-0.25
=(-1.5-0.5)+(2.25-0.25)
=-2+2
=0
(5分之4-3分之1)-(1-5分之1+3分之2)
=4/5-1/3-1+1/5-2/3
=(4/5+1/5)-1+(-1/3-2/3)
=1-1-1
=-1