• 1. 计算下面各题。

  ①6.45-2.74+3.6

  ②45.36+(83.4-15.07)

  ③67.39-(12.67+17.39)

  ④4.5+3.8+15.5

  ⑤35.62-8.38-5.62

  ⑥2.06+5.42+3.94+2.58