Let f(x) be defined for any positive integer x greater than 2 as the sum of all prime numbers less than x. For example, f(4)=2+3=5 and f(8)=2+3+5+7=17. What is the value of f(86)−f(82)? (A) 3 (B) 4 (C) 47 (D) 59 (E) 83

Is every rectangle is a parallelogram? true false

The lines shown below are parallel. if the green line has a slope of -1, what is the slope of the red line?

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.