Percentages

HOW TO SOLVE THIS QUESTION WITHOUT THE HELP OF USING OPTIONS

Q In a local election, 2400 people were to vote for Party A or Party B. Party A was bound to win the election. However, on Election Day, one-third of the voters of Party A were kidnapped. Party B was also able to influence the remaining Party A voters and thus double the strength of its voters. In this way, Party A lost by a majority which was half of that by which it would have won had the elections been fair. How many people finally voted for Party A and Party B?