Rob is balancing his checkbook. his beginning checking account balance was $1. he deposited a check for $77 from his part-time job and $37 in cash that he received in tips into the account. using his debit card, he purchased $25 worth of gas. on a night out with friends, rob used his debit card to spend $8 on a movie ticket and $12 on snacks. rob's mother told him that he needs to put money into a savings account. so rob withdrew the tip money from his checking account and put it into a new savings account. what is rob's checking account balance?

When cell phones were first entering the market, they were relatively large and reception was undependable. all cell phones were essentially the same. but as the technology developed, many competitors entered, introducing features unique to their phones. today, cell phones are only a small fraction of the size and weight of their predecessors. consumers can buy cell phones with color screens, cameras, internet access, daily planners, or voice activation (and any combination of these features). the history of the cell phone demonstrates what marketing trend?