PSLE
The students of a test are divided equally into two groups. In the first group, there are 28 less girls than boys. In the second group, there are 12 less boys than girls. 40% of all the students are girls. How many students are there altogether?

	First group		Second group		Total
Comparison 1	50%		50%		100%
Comparison 2	Boys (more)	Girls (less)	Boys (less)	Girls (more)
	1 u + 28	1 u	1 u + 8	1 u + 8 + 12
Comparison 3	Total girls		Total boys
	40%		60%		100%

Number of students in the first group and the second group is equal.

Percentage of students who are boys
= 100% - 40%
= 60%

Percentage of more boys than girls
= 60% - 40%
= 20%

Total number of boys 
= 1 u + 28 + 1 u + 8
= 2 u + 36

Total number of girls
= 1 u + 1 u + 8 + 12
= 2 u + 20

Number of boys more than girls
= 36 - 20
= 16

20% of the students = 16

1% of the students = 16 ÷ 20 = 0.8

100% of the students
= 100 x 0.8
= 80

Number of students = 80

Answer(s): 80