PSLE
The students of a test are divided equally into two groups. In the first group, there are 54 less girls than boys. In the second group, there are 18 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 + 54	1 u	1 u + 18	1 u + 18 + 18
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 + 54 + 1 u + 18
= 2 u + 72

Total number of girls
= 1 u + 1 u + 18 + 18
= 2 u + 36

Number of boys more than girls
= 72 - 36
= 36

20% of the students = 36

1% of the students = 36 ÷ 20 = 1.8

100% of the students
= 100 x 1.8
= 180

Number of students = 180

Answer(s): 180