A researcher orders a broth of 21.8% glucose for her lab. However, she needs a stronger broth, one that is 51.8% glucose. Fortunately, she has 80.6 liters of 72.4% glucose broth in the stock room. How 51.8% glucose broth can she make? Round your answer to the nearest tenth of a liter.

Solution:

         72.4 * 80.6 + 21.8 * x = 51.8 * (80.6 + x)

                  x = 55.3 litre of 21.8% glucose she has to order.