4 red balls and 5 green balls are selected from $n$ balls. If the sum of both the selections is greater than ${ }^{n+1} C_4$ then the value of $n$ is equal to

A regular polygon has 20 sides. The number of triangles that can be drawn by using the vertices but not using the sides are

The domain of the function $\mathrm{f}(x)={ }^{7-x} \mathrm{P}_{x-1}$ is

Total number of 3-digit numbers, whose g.c.d with 36 is 2 , is