1.-0.5-（-3又1/4）+2.75-(+7又1/2)
=-1/2+13/4+11/4-15/2
=13/4+11/4-1/2-15/2
=24/4-16/2
=6-8
=-2
2.[(2/3-1/2)÷1/30]×(-1/5)
=(1/6 *30)*(-1/5)
=5*(-1/5)
=-1