Sangho uploaded a video to a website where viewers can vote that they like or dislike a video. Each video begins with a score of , and the score increases by for each like vote and decreases by for each dislike vote. At one point Sangho saw that his video had a score of , and that of the votes cast on his video were like votes. How many votes had been cast on Sangho's video at that point?
200
300
400
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600