(1)解:原式=5/2+5/6-1/2+7/6 =15/6+5/6-3/6+7/6 =24/6 =4(2) 解:原式=[(-9)*1/9-0.8]*5/27 =(-1-0.8)*5/27 =-(9/5)*5/27 =-(1/3)