Answer:
4%
Step-by-step explanation:
1) Subtract the base price from the final price. 40.56 - 39 = 1.56.
2) Divide the tax by the base price to determine the decimal version of the percentage. 1.56 / 39 = 0.04.
3) Multiply this by 100 to turn it into the normal percentage. 0.04 × 100 = 4, so the answer is 4%.