Suppose you receive $100 for a graduation present, and you deposit it in a savings account. then each week thereafter, you add $5 to the account but no interest is earned. the amount in the account is a function of the number of weeks that have passed. use your equation to find when you will have $310 in the account.

You’re ordering more thread for blue jeans co. you usually purchase from ted’s threads, which sells 12 thread spools for $27. you recently received a notice from wade's wares that says you can buy thread from them for $2.30 each for the first 2 dozen and $2 a spool thereafter. you need to order 5 dozen spools. what percentage can you save by going with wade’s wares?