Catie is 3 years older than her brother. the sum of their ages is no more than 31. write an inequality that can be used to represent this situation, where x represents catie's brother's age. don’t combine like terms.

Ascientist wants to use a model to present the results of his detailed scientific investigation. why would a model be useful? a )because the model makes the concepts easier to understand b) because the model is easy to put together and to use c) because the model prevents other scientists from asking questions d) because the model requires the audience to pay full attention to it i don't know what to choose because between a and d a is much more likely than d because it only wants to get the attention of the audience. i'm confuse.