1 : Number of Straight lines possible by joining 10 points in the plane (When no 3 or more than 3 points are collinear), selecting 2 points at a time = 10C2 = 45
Similarly, Number of Straight lines possible by joining 4 points in the plane (When no 3 or more than 3 points are collinear), selecting 2 points at a time = 4C2 = 6
In the question, given 4 points are collinear, and since all the collinear points when joined pair wise form only One straight line,
Thus, required number of straight lines : = 10C2 - 4C2 + 1 = 40.
2 : The number of triangles that can be formed by 10 points (when no 3 points are collinear) = 10C3.
Similarly, the number of triangles that can be formed by 4 points (when no 3 points are collinear) = 4C3.
In the question, given 4 points are collinear, and 4 collinear points cannot form a Triangle when taken 3 at a time. ( With 3 or more Collinear points we cannot form any Triangle by joining any 3 of them.)
Thus, required number of triangle can be formed : = 10C3 - 4C3 = 120 - 4 = 116.