If 2/5 of the books in the library are fiction and 1/4 of the fiction books are science fiction, what fraction of the books in the library are science fiction? HELP

Kelly is a salesperson at a shoe store, where she must sell a pre-set number of pairs of shoes each month. at the end of each work day the number of pairs of shoes that she has left to sell that month is given by the equation s=300-15x , where s is the number of pair of shoes kelly still needs to sell and x is the number of days she has worked that month. what is the meaning of the number 300 in this equation

In a graph with several intervals o data how does a constant interval appear? what type of scenario produces a constant interval?

Does the point (1, sqrt 7) lie on circle shown.