Determine wether or not the equations represent a direct variation. Sort the equations into the appropriate category

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.

If cos(2x) = tan^2(y), show that cos(2y) = tan^2(x).

Awasher and a dryer cost $701 combined. the washer costs $51 more than the dryer. what is the cost of the dryer?