Out of $10$ points in a plane,$6$ are in a straight line. The number of triangles formed by joining these points is:

There are $10$ points in a plane,of which no three points are collinear except $4$. Then,the number of distinct triangles that can be formed by joining any three points of these ten points,such that at least one of the vertices of every triangle formed is from the given $4$ collinear points is

Three parallel straight lines $L_1, L_2$ and $L_3$ lie on the same plane. Consider $5$ points on $L_1, 7$ points on $L_2$ and $9$ points on $L_3$. Then the maximum possible number of triangles formed with vertices at these points is:

Six '$X$'s have to be placed in the squares of the figure such that each row contains at least one '$X$'. In how many different ways can this be done?

There are $10$ points in a plane,out of which $4$ are collinear. How many straight lines can be formed by joining any two of these points?

Find the number of marked points on the plane,if when connected pairwise by line segments,the total number of line segments formed is $15$.