Cthe functions that are called in the main() function to produce these outputs. enter the monthly sales: 14550.00 enter the amount of advanced pay, or enter 0 if no advanced pay was given advanced pay: 100 requirements for the function - determine_comm_rate() sales less than 1.00 rate: .10 sales from 1.00 to 14999.99 rate: .12 sales from 15000.00 to 17999.99 rate: .14 sales from 18000.00 to 21999.99 rate: .16 sales greater than 21999.99 rate: .18

Following are the program in the C programming Language:

#include <stdio.h>  //header file  

//set function for sales

int get_sales(){

int sale;

//print message

printf("Enters monthly sale: ");

scanf("%d",&sale);

return sale;

}

//set function for the advance payment

int get_advanced_pay(){

int advance;

//print message

printf("Enter the amount of advanced pay or enter 0 if no advanced pay was given: ");

scanf("%d",&advance);

return advance;

}

//set fucntion of comman rates

float determine_comm_rate(int sale){

  if(sale<10000)

      return 0.1;

  if(sale<15000)

      return 0.12;

  if(sale<18000)

      return 0.14;

  if(sale<22000)

      return 0.16;

  else

      return 0.18;

}

//set the main function

int main(){

int sale,advanced;

float comm_rate,pay;

sale=get_sales();

advanced=get_advanced_pay();

comm_rate=determine_comm_rate(sale);

pay=sale*comm_rate-advanced;

printf("The pay is %f\n",pay);

if(pay<0)

//if the pay is less than 0

printf("The salesperson must reimburse the company");

}

Output:

Enters monthly sale: 45000

Enter the amount of advanced pay or enter 0 if no advanced paywas given: 1000

The pay is 7100.000488

Explanation:

Here, we set the integer type function "get_sales()" in which we get the monthly sale of the person and then return sales.

Then, we set the function "get_advanced_pay()" in which we get the advance payment of the person and then return it.Then, we set the function "determine_comm_rate()" in which we compare their sales and return it.

Finally, we set the main method in which we call both the functions and print the following output.

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