脱式计算（1（5分之4—3分之2）*250%（2）2除以25分之4除以12分之5（3）8分之7—（0.5—25%）除以16分之7

(1)(4/5-2/3)*250%
=(12/15-10/15)*250%
=(2/15)*250%
=1/3
(2)2/(4/25)/(5/12)
=2*(25/4)/(5/12)
=(25/2)/(5/12)
=(25/2)*(12/5)
=30
(3)7/8-(0.5-25%)/(7/16)
=7/8-(0.5-0.25)/(7/16)
=7/8-(0.25)*(16/7)
=7/8-4/7
=49/56-32/56
=17/56