Dara needs to mails three packages that weigh 6.1, 6.5, and 6.8 pounds. the mail delivery service that dara uses rounds the weight of a package to the nearest pound to determine the price of shipment. it costs $2 to mail a package that weighs 6 pounds and $2.75 for packages that weigh 7 pounds. (a) how much would dara pay to ship each individual package? (b) dara has $7.25 in cash to spend. show how subtraction can be used to determine whether dara has enough to mail the three packages and how much extra money she has or needs.