<PRE><B>Question 936407</B>
 4 points are needed to form a quadrilateral
 we need to select 4 points out of 25 points
 so no of quadrilaterals that can be formed out of 25 points  = 25c4
                                                   ={{{(25*24*23*22)/(4*3*2*1)}}}
                                                    =25*23*22
                                                    =12650
but out of 25 points , 7 points are collinear( which lies on same line)
 so they form a line . they cannot form quadrilaterals
  so no of quadrilaterals that cannot be formed due to collinear points  = 7c4
                                              ={{{(7*6*5*4)/(4*3*2*1)}}}
                                              ={{{7*5}}}
                                              =35 
  no of quadrilateral can be formed from 25 points out of which 7 are collinear are  = 12650-35
     =12615
 Result : 12615</PRE>