Twenty different books are to be put on five book shelves, each of which holds at least twenty books.
(a) how many different arrangements are there if you only care about the number of books on the shelves (and not which book is where)?
(b) how many different arrangements are there if you care about which books are where, but the order of the books on the shelves doesn't matter?
(c) how many different arrangements are there if the order on the shelves does matter?

Simplify the algebraic expression 8y-2(y+4)

Farmers know that driving heavy equipment on wet soil compresses the soil and injures future crops. here are data on the "penetrability" of the same type of soil at two levels of compression. penetrability is a measure of how much resistance plant roots will meet when they try to grow through the soil. compressed soil 2.85 2.66 3 2.82 2.76 2.81 2.78 3.08 2.94 2.86 3.08 2.82 2.78 2.98 3.00 2.78 2.96 2.90 3.18 3.16 intermediate soil 3.17 3.37 3.1 3.40 3.38 3.14 3.18 3.26 2.96 3.02 3.54 3.36 3.18 3.12 3.86 2.92 3.46 3.44 3.62 4.26 use the data, omitting the high outlier, to give a 95% confidence interval for the decrease in penetrability of compressed soil relative to intermediate soil. compute degrees of freedom using the conservative method. interval: to

Will mark brainliest! ( explain the answer too, it can be one sentence)