Let y=x! and z = (2x)! If (z / y) = 120 then what is the value of (3x)!?

Let n be a natural number. The number of consecutive zeros at the end of the expansion of n! is exactly 2. How many values of n are possible?

How many 4-digit numbers that are divisible by 4 can be formed using the digits 1, 2, 3 and 4 (repetition of digits is not allowed)?

For the following two (02) items:
There are 8 points on a plane out of which 4 points are collinear.

How many triangles can be formed by joining these points?