计算．
①7.5×1.8÷0.15     ②12.4÷0.8﹣9.64        ③7.65×2.4+1.64
④12.3﹣10.8÷4.5    ⑤44.28÷4.1÷0.9+2.5    ⑥39.87×4.58﹣29.87×4.58．