Below is an instruction that describes a task. Write a response that appropriately completes the request in Chinese. Please answer in Chinese.

### Instruction:
 珍妮为义卖会带来了40块花生酱饼干和50块巧克力曲奇饼干。马库斯带来了30块花生酱饼干和20块柠檬饼干。如果对花生过敏的蕾妮随机挑选一个饼干，她会有过敏反应的几率是多少，以百分比表示？


### Response:
 首先找出花生酱饼干的总数：40块花生酱饼干 + 30块花生酱饼干 = <<40+30=70>>70块花生酱饼干
然后通过将花生酱饼干的数量加上其他两种类型的饼干的数量，找出饼干的总数：70块花生酱饼干 + 50块巧克力曲奇饼干 + 20块柠檬饼干 = 140块饼干
然后将花生酱饼干的数量除以总饼干数量，并乘以100%以找出蕾妮得到花生酱饼干的百分比几率：70块花生酱饼干 / 140块饼干 * 100% = 50%