John O'Hagan has just returned from a sales convention in Puerto Vallarta, Mexico where, to win a bet he made with Marjory Duffin (who was also at the convention), he went bungee jumping at a nearby mountain retreat. The bungee cord he used had the property that a person weighing70kilogramswould drop a total distance of74.5 meters,while a90kgperson would drop91.5meters.Express the distanceda jumper drops as a linear function of the jumper's weightw

a) d(w)=

b)John O'Hagan dropped85meters.What was his approximate weight? (Round your answer to the nearest kilogram.)