Answer:
To find the price of the most expensive book that Peggy could buy, we need to consider the effects of the discount and the tax.
Let's assume the price of the book before the discount is x dollars.
After applying the 15% discount, the price of the book becomes 85% of x, which is (0.85 * x) dollars.
Next, we need to add the 7% tax to the discounted price. The price after tax is (1 + 0.07) times the discounted price, which is (1.07 * 0.85 * x) dollars.
We know that Peggy has $30 to spend, so we can set up the equation:
(1.07 * 0.85 * x) = 30
Simplifying the equation:
0.7245x = 30
Dividing both sides by 0.7245:
x = 30 / 0.7245
x ≈ 41.37
Therefore, the price (before the discount) of the most expensive book that Peggy could buy is approximately $41.37.