evaluated = difference.evaluate();
System.out.printf("%s = %s%n", difference, evaluated);
assertEquals(evaluated, new LongRationalNumber(1, 6));
RationalNumber sixEighth = new LongRationalNumber(6, 8);
evaluated = sixEighth.evaluate();
System.out.printf("%s = %s%n", sixEighth, evaluated);
assertEquals(evaluated, new LongRationalNumber(3, 4));
difference = new Subtraction(new LongRationalNumber(2, 3), new LongRationalNumber(1, 6));
evaluated = difference.evaluate();