Please help me it is very much appreciated

What is the value of x in the equation 2(x-4) = 4(2x + 1)?

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.

Awater tank holds 18000 gallons. how long will it take for the water level to reach 6000 gallons if the water is used at anaverage rate of 450 gallons per day