I don’t understand this problem can someone please help !

Apublic library wants to place 4 magazines and 9 books on each display shelf. the expression 4s+9s represents the total number of items that will be displayed on s shelves. simplify the expression

1mile equals approximately 1.6 kilometers. which best approximates the number of miles in 6 kilometers?

F(x) = 1/x g(x)=x-4 can you evaluate (g*f)(0) ? why or why not?