The textbook is $150 originally, so to find the price of the textbook on sale, multiply the original price by 12% (0.12). Then subtract 12% of 150 from 150.
150 * 0.12 = 18
Subtract 18 from 150.
150 - 18 = 132
Multiply the price of the textbook on sale by the sales tax of 8.25% (0.0825). Then add the tax price onto the sale price of the textbook.