A man can finish drinking a barrel of orange juice in $$15$$ days on his own. If he shares the barrel of orange juice with his wife, they can finish it in $$12$$ days. How many days will his wife take to finish drinking the same barrel of orange juice on her own? 
Overseas Competition->Knowledge Point->Word Problem Modules->Solving Problems Involving Proportions->Ratio Word Problems with Invariant Sums