Bobby bought 5 textbooks. The original price of each textbook was $30. He was given 15% discount on the first textbook and 20% discount on the rest of the textbooks. How much did he pay for the 5 textbooks altogether?
Cost of the first textbook after 15% discount in percent
= 100% - 15%
= 85%

Cost of the first textbook after discount
= 85% x 30
= ⁸⁵₁₀₀ x 30
= $25.50

Number of the rest of the textbooks that enjoyed 20% discount
= 5 - 1
= 4

Cost of each of the rest of the 4 textbooks after 20% discount in percent
= 100% - 20%
= 80%

Cost of each of the rest of the 4 textbooks
= 80% x 30
= ⁸⁰₁₀₀ x 30
= $24

Cost of the rest of the 4 textbooks that enjoyed 20% discount
= 4 x 24 
= $96

Total cost for the 5 textbooks
= 25.50 + 96
= $121.50

Answer(s): $121.50