What does this question mean? i needs !

Mindy bought 5/8 pound of almonds and a 3/4 pound of walnuts. which pair of fraction cannot be used to find how many pounds of nuts she bought in all.

Question b of 10which of the following describe an angle with a vertex at a? check all that applyo a. labcов. савd dooo c_baco d. zacb

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.