One group (A) contains 280 people. Two-fifths of the people in group A will be selected to win $50 fuel cards. There is another group (B) in a nearby town that will receive the same number of fuel cards, but there are 683 people in that group. What will be the ratio of nonwinners in group A to nonwinners in group B after the selections are made? Express your ratio as a fraction or with a colon.