Julia has gone to the store to inquire about mailing packages. she is told that the cost of postage depends on the weight of the package where packages less than 10 lbs follow one model and packages greater than or equal to 10 lbs follow another model. she needs to be able to estimate her shipping costs so that she can price the items she wants to sell appropriately to include the cost of shipping and knows that the majority of time her packages weigh more than 10 lbs. she finds that she can mail a 10 pound package for $5.10 and a 15 pound package for $8.85.which equation best models the cost of shipping a package, if x represents the weight of the package and y represents the cost? a)y = 5xb)y = 0.75xc)y = 0.75x - 2.4d)y = 1.33x - 8.2