In a school, 0.9 of the boys and 0.1 of the girls take part in curricular activities. There is an equal number of girls and boys who do not take part in curricular activities. If 1230 students take part in curricular activities, how many less students do not take part in curricular activities than those who take part in curricular activities?

Boys		Girls
Take part	Do not take part	Take part	Do not take part
9x9	1x9	1	9
	1x9		1x9
81 u	9 u	1 u	9 u

0.9 = ⁹₁₀
Boys that take part : Boys that do not take part = 9 : 1

0.1 = ¹₁₀
Girls that take part : Girls that do not take part = 1 : 9

The number of girls who do not take part is repeated.  Make the number of girls who do not take part the same.  LCM of 1 and 9 is 9.

Number of students who take part in curricular activities
= 81 u + 1 u
= 82 u

82 u = 1230

1 u = 1230 ÷ 82 = 15

Number of students who do not take part in curricular activities
= 9 u + 9 u
= 18 u

Number of less students who do not take part in curricular activities than those who take part in curricular activities
= 82 u - 18 u 
= 64 u
= 64 x 15
= 960

Answer(s): 960