The book is $7.50, and the sales tax is 6%. We just multiply 7.50 times 0.06, which is 0.45. So the tax on the book would be 45 cents. Next, add 7.50 with 0.45. This gives us 7.95. The cost of the book after sales tax is $7.95. He brought $8 with him. So yes, he does have enough money to buy the book, and he would get 5 cents back as change