问题 解答题
计算下面各题(能简算的要简算).
15×[120-(42+36)]
55×25-25×45425+21×(12+28)
答案

(1)15×[120-(42+36)]

=15×[120-78]

=15×42

=630;

(2)55×25-25×45

=(55-45)×25

=10×25

=250;

(3)425+21×(12+28)

=425+21×40

=425+840

=1265.

单项选择题