i have to purchase over a $100 dollars i'm buying 5 books @ $12.79 and a few CDs @ $6.99 how many CDs x can I order to get few shipping

Question

can you show me how to work this problem in algebra form

Answer 1

So you are spending  5x12.79 on books. If you let c represent the number of CDs, then you spend cx6.99 on them.

 

Your total, which is  5(12.79) + c(6.99) must be more than 100 to get free shipping.

 

So you have the inequality  5(12.79) + 6.99c > 100

 

63.95 + 6.99c > 100

 

Subtract 63.95 from both sides:     6.99c > 36.05

 

Divide both sides by 6.99:             c > 5.157

 

c has to be a whole number, so you need to buy at least 6 CDs to get free shipping.

 

Check this before you order   5 books cost 63.95 and 6 CDs cost  41.94, so the total is  $105.89, which is more than 100.