Let x is number of girls going (x>0).
Since the bus cost 360, each of them paid: [tex] \frac{360}{x} [/tex]
If they got 3 more, each would pay: [tex] \frac{360}{x+3} [/tex]
According to statement:[tex] \frac{360}{x} [/tex] - 6 = [tex] \frac{360}{x+3} [/tex]
⇒(360 - 6x)(x+3) = 360x
⇒360x - 6x^2 +3*360 -18x = 360
⇒6x^2 + 18x - 3*360 = 0
⇒6(x-12)(x+15) = 0
⇒x = 12 (because x > 0)
Thus, 12 girls went.
