PLEASE HELP!! INTRAVENOUS RATE ASSISTANT !!!

[casescs]

If I click number 1 the output should be like this
Problem => 1
Enter rate in ml/hr=> 150
Enter tubing’s drop factor (drops/ml)=> 15
The drop rate per minute is 38.

but the output in "The drop rate per minute is" in my code is always 0 what should I do?

#include<stdio.h>
#include<conio.h>
#include<windows.h>

int get_problem(void);
void get_rate_drop_factor(float ml_hr, float drops_ml);
float fig_drops_min(float ml_hr, float drops_ml);




int y;
float answer;

	
int main (void)

{
	float ml_hr, drops_ml;    //problem number 1	
	
	y = get_problem();
	
	do
	{

			if (y == 1) 
				{
					get_rate_drop_factor(ml_hr,drops_ml);
					answer = fig_drops_min(ml_hr,drops_ml);
					printf("\tThe drop rate per minute is %.0f",ceil(answer));
					getch();
					system("cls");		
				}
			}
	void get_rate_drop_factor(float ml_hr, float drops_ml)
	{
		printf("\tEnter rate in ml/hr: ");
		scanf("%f", &ml_hr);
		printf("\tEnter tubing factor (drops/ml): ");
		scanf("%f", &drops_ml);
	}
	
	float fig_drops_min(float ml_hr, float drops_ml)
	{
		return ml_hr*drops_ml/60;
	}
	

[cire]

void get_rage_drop_factor(float& ml_hr, float& drops_ml)