Question

In a class, if every student gives a rose to every other student and the total number of roses is $240$, how many students are there in the class ?

Answer 1

Let number of students in the class were xx Roses posses by single student $=240$
$x\times (x-1)=240$
$x^2-x-240=0$
$x^2-16x+15x-240=0$
$x=16,-15$
$x$ is the number of students so it cannot be negative.

So, $x=16$