Answer:
Amount of grapes eaten by Frank = 2/ 15 pounds
Explanations:
Amount of grapes bought by Frank on Monday = 4/5 pounds
Amount of grapes Frank has left on Tuesday = 2/3 pounds
Amount of grapes eaten by Frank = (Amount of grapes bought on Monday) - (Amount of grapes left on Tuesday)
Amount of grapes eaten by Frank = 4/5 - 2/3

Amount of grapes eaten by Frank = 2/ 15 pounds