I need one solution for 3x -3_x+ 11

Which property is illustrated by the following statement? if hxa rgi, then rgi hxa.

Determine whether the set of whole numbers is closed under addition. explain why the set is or is not closed. give an example.

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.