For the following problem, draw a bar model (complete with a…

For the following problem, draw a bar model (complete with a question mark, answer statement, and all the information given in the problem displayed on the model) and write a unit Teacher’s solution that answers the question.  3002 exercise books are arranged into 3 piles.  The first pile has 10 more books than the second pile.  The number of books in the second pile is twice the number of books in the third pile.  How many are there in the third pile?  

A 700 gallon tank initially contains 100 gallons of a mixtur…

A 700 gallon tank initially contains 100 gallons of a mixture of 10 lb of salt dissolved in water.  At time t=0, water containing 0.5 pounds of salt per gallon flows into the tank at a rate of 3 gallons per minute, and the well-stirred mixture leaves at the rate of 2 gallons per minute. How much salt is in the tank when it contains 500 gallons of the mixture?