¹₂ of the pupils in a school were boys and the rest were girls. ³₄ of the boys and ¹₅ of the girls took part in a school event. 210 pupils did not take part. How many more girls were needed to take part in the school event so that it would be equal to the same number of boys who took part in the event?

Boys		Girls
1x20 = 20 u		1x20 = 20 u
Took part	Did not take part	Took part	Did not take part
3x5	1x5	1x4	4x4
15 u	5 u	4 u	16 u

Since ¹₂ of the pupils in a school were boys and the rest were girls, the total number of boys and girls is the same.
The total number of boys is repeated and the total number of girls is repeated.

Make the total number of boys and the total number of girls the same since they are equal. LCM of 4 and 5 is 20.

Number of pupils who did not take part
= 5 u + 16 u
= 21 u

21 u = 210

1 u = 210 ÷ 21 = 10

Number of more girls that were needed to take part in the school event so that it would be equal to the same number of boys who took part in the event
= 15 u - 4 u
= 11 u
= 11 x 10
= 110

Answer(s): 110