<PRE><B>Question 339182</B>
let boys be x
girls be y
..
total students = x+y
..
60 % are boys
..
Number of boys = 0.6(x+y)
Number of girls = 0.4(x+y)
..
When you add 6 boys to the class
The number of boys = 0.6(x+y)+6
..
The total remains the same.(x+y)
The boys increases to 75% of total = 0.75(x+y)
..
0.6(x+y)+6=0.75(x+y)
0.6x+0.6y+6 = 0.75x+0.75y
add -0.6x and -0.6y to both sides
0.6x-0.6x+0.6y-0.6y+6 = 0.75x+0.75y-0.6x-0.6y
6 = 0.15x+0.15y
6=0.15(x+y)
divide by 0.15
6/0.15 = 0.15/0.15 * (x+y)
x+y= 40
..
on the first day 60% were boys
60% of 40 are boys
0.6 * 40 = 24 boys.
..
the balance 16 were girls on the first day.
..
CHECK
add 6 +24 = 30
30/40 = 3/4 = 75%</PRE>