50 Is a(n) of 10 because 5×10 = 50

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.

Eric drove 275 miles in 5 hours. at the same rate how long would it take him to drive 495 miles?

Which of the following constants can be added to x2 - 3x to form a perfect square trinomial?