求解：这种题中含有未知数的DS题到底算未知还是已知

Graceduoduo

In a product test of a common cold remedy, x percent of the patients tested experienced side effects from the use of the drug and y percent experienced relief of cold symptoms. What percent of the patients tested experienced both side eddects and relief of cold symptoms?

(1) Of the 1,000 patients tested, 15 percent experienced neither side effects nor relief of cold symptoms.

(2) Of the patients tested, 30 percent experienced relief of cold symptoms without side effects.

如题，答案是E；但我选的是D，因为默认x,y是已知具体数字的情况下，1）和2）都是可以单独表达出两事件的交集的。是不是我理解错了？谢谢大家。