What are the cycles per second in the simple harmonic motion described by d=8 cos (pi/2)t? what is the time per second, required per cycle?

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

Given abcd ac=38 and ae=3x+4 find the value of x

Maurice has 54 fewer comic books than rebecca.they have 130 comic books together .how many comic books are in maurices collection ? how many comic books are in rebeccas collection