¹₂ of the children in a school were boys and the rest were girls. ³₅ of the boys and ¹₄ of the girls took part in a school event. 345 children 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
3x4	2x4	1x5	3x5
12 u	8 u	5 u	15 u

Since ¹₂ of the children 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 5 and 4 is 20.

Number of children who did not take part
= 8 u + 15 u
= 23 u

23 u = 345

1 u = 345 ÷ 23 = 15

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
= 12 u - 5 u
= 7 u
= 7 x 15
= 105

Answer(s): 105