onathan collects postcards and stamps. The number of postcards in his collection is 12 more than the number of stamps. He has 39 postcards in all. If Jonathan has x stamps, which equation represents this situation and how many stamps does he have?

This size running track is usually called a 400 meter track. however if a person ran as close to the inside as possible on the track they would run less than 400 meters in one lap. how far away from the inside border would someone have to run to make one lap equal exactly 400 meters