$2.$The image below shows the gas cap door on a friend's car. Can you guess how to open it$?$ The first time my friend went to put gas in his car he spent about half an hour at the gas station trying to figure out how to open his gas cap door! He looked everywhere for some knob to pull to release the gas cap door. He looked under the dashboard, in the glove box, behind the seats, in the trunk. The gas station attendant didn't know how to open it either. Finally someone drove in to get gas who knew the secret. You just push on one edge of the gas cap door, and it opens! Wow, it only took $1/2$ hour to figure out how to do something that should have been immediately obvious!