How do I get the right answers?

/* 	Program:		prog3.cpp
	By:				Mackenzie Ritter
	Last Modified:	Oct 31, 2017
	Purpose:		To give customer their cost based on amount of books purchased.
	Notes:
*/
#include 
#include 

using namespace std ;

void Instructions () ;
void numBooks () ;
void totalCost (int) ;
void percentoff (float) ;
void finalCost (float, float) ;
void receipt (int, float, float, float) ;

int main ()
{
	int books ;
	float total, cost, discount ;
	Instructions () ;
	numBooks () ;
	totalCost (books) ;
	percentoff (total) ;
	finalCost (discount, total) ;
	receipt (books, total, discount, cost) ;	
}

void Instructions ()
{
	cout > books ;
}

void totalCost (int books)
{
	float total = books * 8.99 ;
}

void percentoff (float total)
{
	float discount = 0.15 * total ;
}

void finalCost (float discount, float total)
{
	float cost = total - discount ;
}

void receipt (int books, float total, float discount, float cost)
{
	cout << books << endl ;
	cout << "$" << total << endl ;
	cout << discount << "% off" << endl ;
	cout << "$" << cost << endl ;
}