First you must take 15% of 166.96 dollars, the final value that can be taxed.
Convert 15% to a decimal: 15/100 = 0.15
166.96 x .15 = 25.044
25.044 is what you get OFF, so you have to subtract that fromt he original price,
166.96 - 25.044 = 141.916
141.916 is your total "taxable" value (what you spent on it and will pay for a the register), so now you apply your sales tax
Convert 8% to decimal form
8/100 = .08
141.916 x .08 = 11.353
Now because you have to pay the tax, you add that onto your final value (141.916), to get a grand total of:
141.916 + 11.353 = 153.27 dollars
Hope that helped!