The sugar water inequality was learned in the second volume of Grade 8. Sugar water inequality, a gram of sugar water has b grams of sugar (a >; b> ), the mass ratio of sugar to sugar water is b/a, and if c grams of sugar (c >; ), the mass ratio of sugar to syrup is (b+c)/(a+c). Life experience tells us that sugar water will be sweeter after adding sugar, and the inequality can be obtained: (b+c)/(a+c)> b/a(a> b> ，c> )。 It is called "sugar water inequality".