3) Take the original price and subtract the original price * the discount percentage
99.50 - (99.50 * 0.50)
99.50 - 49.75
49.75
Option C is your answer.
4) Take the original price and add the original price * the tax rate
99.50 + (99.50 * 0.04)
99.50 + 3.98
103.48
Option D is your answer.
5) Take the original price and add the original price * the markup rate
3.95 + (3.95 * 0.20)
3.95 + 0.79
4.74
Option D is your answer.