脱式计算，能简算的要简算．
①85×54÷18+745             ②3.4÷[（1.25+0.45）×2]           ③1080+270÷18﹣864
④7.54++2.46+          ⑤（2.4﹣）÷0.625+           ⑥98.9×99+98.9．