<PRE><B>Question 998781</B>
Let the number of students initially be x

so cost per student = 225,000/x

5 more joined

cost per student = 225,000/(x+5)

difference is 500

225000/x - 225000/(x+5) =500

multiply by x(x+5)

225000(x+5) -225000x= 500(x)(x+5)

225000x+1125000-225000x = 500x^2+2500x

500x^2+2500x-1125000=0

/500
x^2+5x-2250=0

x^2+50x-45x-2259=0

x(x+50) -45(x+50)=0

(x+50)(x-45)=0

x = -50 or 45

discard -50

answer 45 students initially</PRE>