Writing an algeabric expression

Question

Answer each question. Then write an expression that can be used to solve for any input. Be sure to define the variable

 

Mr. Hartman joined the Book of the month club. In his first order, he received an initial 3 books for $.30 each, In the same order, he also bought a number of additional books for $9.99 each. If he spent $70.23 on his total order, how many books did he buy?

Answer 1

b represents the number of additional books

9.99b represents the money he spent on additional books

3(0.30) represents the money he spent on the initial three books

 

70.23 = 3(0.30) + 9.99b

70.23 = 0.90 + 9.99b             multiply

69.33 = 9.99b                         subtract 0.90 form both sides

6.03993994 = b                     divide both sides by 9.99

 

Check the numbers.