1 files changed, 4 insertions, 4 deletions
diff --git a/classes/Discount.php b/classes/Discount.php
index 7216615..4084d43 100644
--- a/classes/Discount.php
+++ b/classes/Discount.php
@@ -24,8 +24,8 @@
 /**
  * An interface to the discount table in the database
  */
-class Discount extends Model {
-	use Calculatable;
+class Discount extends Model implements Calculatable {
+	use StandardCalculatable;
 
 	public
 		$table = 'discount',
@@ -50,11 +50,11 @@ class Discount extends Model {
 		return $pd->text($this->description);
 	}
 
-	protected function calculateSubtotal() {
+	public function calculateSubtotal() {
 		return - $this->value;
 	}
 
-	protected function calculateVAT() {
+	public function calculateVAT() {
 		return $this->calculateSubtotal() * $this->VAT_percentage / 100;
 	}
 }