Question
The number of boys in the lecture hall was 49 that of the girls. There were 170 more girls than boys. After some girls had left the lecture hall, the number of boys at the lecture hall was four times the number of the remaining girls. How many girls left the lecture hall?
4 m

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The number of boys in the lecture hall was 49 that of the girls. There were 170 more girls than boys. After some girls had left the lecture hall, the number of boys at the lecture hall was four times the number of the remaining girls. How many girls left the lecture hall?