CalculateCost.java

package cost;

public class CalculateCost {

	// calculate the sms cost
	public static double smsCost(int qty) {
		return 65 * qty;
	}

	// calculate the call cost
	public static double callCost(int seconds) {
		final int PER_SECOND_PRICE = 15;
		return PER_SECOND_PRICE * seconds;
	}

	public double calc() {
		return 0.0;
	}

}

TotalCost.java

import cost.CalculateCost;

public class TotalCost {
	public static void main(String[] args) {
		
		// I sent 7 SMS's and made 3 calls of 37, 23 & 12 seconds.
		// what is the total cost

		double totalCost =
			CalculateCost.smsCost(7) +
			CalculateCost.callCost(37) +
			CalculateCost.callCost(23) +
			CalculateCost.callCost(12);

		System.out.println("Total cost: R" + totalCost/100);

	}
}