计算下面各题，能简算的要简算．
8.5×（2.36+2.42）÷0.25       3.9÷1.3×6             4.25×6.3+3.7×4.25
205×99                        25.6﹣7.49﹣2.51        2.5﹣（6.8﹣4.9）×0.8．