There are 10 points in a plane no three of which are in the same straight line, excepting 4 points, which are collinear.
Find the probability that
(i) number of straight lines obtained from the pairs of these points.
(ii) number of triangles that can be formed with the vertices as these points.
Out of 18 points in a plane, no three are in the same straight line except 5 points which are collinear. How many straight lines can be formed by joining them?