Question

Ahn 选择一个两位整数，从 $200$ 中减去它，再把结果加倍。Ahn 能得到的最大数是多少？

Ahn chooses a two-digit integer, subtracts it from $200,$ and doubles the result. What is the largest number Ahn can get?

$200$

$202$

$220$

$380$

$398$

知识点：最优化

要得到最大结果，应从 $200$ 中减去最小的可能数。

最小的两位数是 $10$ 。让 Ahn 选择十，最终得到 $2 (200 - 10) = 2 \cdot 190 = 380$

所以正确答案是 D。

To get the largest number, we would want to subtract the smallest number possible from $200.$

The smallest two-digit number is $10.$ Having Ahn choose this number will give us $2 (200 - 10) = 2 \cdot 190 = 380$ as the final result.

Thus, D is the correct answer.