脱式计算（能简算的要简算）
2.4×1.5+3.6×1.5          0.125×2.5×8       7.38﹣5.14+3.62﹣2.86
17.2﹣7.2×0.6             8.9×9.9            41.9﹣2.08﹣7.92．