A bag of toffee is $7$ dollars, a bag of cotton candy is $6$ dollars, and a bag of orange candy is $15$ dollars. Now, the candy shop decides to mix $40$ bags of toffee, $50$ bags of cotton candy, and $10$ bags of orange candy for $100$ bags of assorted candy. What should be the price of the assorted candy in dollars to keep the total revenue unchanged? 
Overseas Competition->Knowledge Point->Word Problem Modules->Average Problems 
Total revenue: $40\times 7+50\times 6+10\times 15=730$ dollars  A bag of assorted candy: $$730\div 100=7.3$$ dollars 