Marco is reconstructing his expenses for the past two weeks. Here are the records of his expenses: Transaction
Cost ($)
T-shirt
20
Gas
22
Movie
13
Video game
39
Jeans
34
Hat
15
Books
31

Marco’s bank statement says that he has an ending balance of $81. What is Marco’s starting balance?

Which one ? is the answer and how to find this answer

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.

Given that abcd is a rhombus, what is the value of x?