11. By weight, liquid A makes up 8 percent of solution R and 18 percent of solution S. If 3 grams of solution R are mixed with 7 grams of solution S, then liquid A accounts for what percent of the weight of the resulting solution?
A. 10%
B. 13%
C. 15%
D. 19%
E. 26%
答案及解析：
答案：C
(3×8%+7×18%)/(3+7)=15%， A makes up B是“B由A组成”，不要看反哦~
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