Best choice for variables.....I would let students be " s " and parents be " p "
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.
Subtract 18 from 150.
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.
Add 10.89 to 132.
The final price of the textbook is $142.89.
Answer:

Step-by-step explanation:

They need to sell 33, unless you round it up then 34.