added testcase for multiplication where the result needs to be reduced and updated the code accordingly

src/main/py/fractions.py

@@ -22,4 +22,6 @@ def addFractions(num1, denom1, num2, denom2):
     return reduceFraction(result_num, denom1)
 
 def multiplyFractions(num1, denom1, num2, denom2):
-    return (num1 * num2, denom1 * denom2)
+    result_num = num1 * num2
+    result_denom = denom1 * denom2
+    return reduceFraction(result_num, result_denom)

src/test/py/test_fractions.py

@@ -30,6 +30,9 @@ class fractions(unittest.TestCase):
     def test_multiply_fractions_1_by_2_and_1_by_2_should_be_1_by_4(self):
         self.assertEqual(multiplyFractions(1,2,1,2), (1,4))
 
+    def test_multiply_fractions_1_by_5_and_5_by_3_should_be_1_by_3(self):
+        self.assertEqual(multiplyFractions(1,5,5,3), (1,3))
+
 
 if __name__ == '__main__':
     unittest.main()