#percentageofapercentage
Original no. of girls
80 `xx` `40/100` = 32
Original no. of boys
80 `xx` `60/100` = 48
The percentage of boys in the end
20%
20% = 48
No. of pupils in the end
100% = 48 `-:` 2 `xx` 10 = 240
#percentageofapercentage
(part a):
Percentage of female
100% - 60% = 40%
20% of the female left in the afternoon, so the percentage of people who left
`20/100` `xx` 40% = 8%
(part b):
60% of people - 33 of male = 75% of people
`->` 60u - 33 = 75% of people
40% - 8% - 35 of female = 25% of people
32% of people - 35 of female = 25% of female
`->` 32u - 35 = 25% of people
96u - 105 = 75% of people
60u - 33 = 96u - 105
105 - 33 = 96u - 60u
36u = 72
1u = 72 `-:` 36 = 2
1u = 1%
100u = 2 `xx` 100 = 200
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