[SoLiDUS]

My own creations: the first is rather easy, the second depends on your level
of base 2, 8 or 16 knowledge and finally, the third will have you tearing your
hair out. Have fun...

This is an analogy.
y = 3(x - 5) : L :: y = (x - 1)(x + 1) : ?

The second is related to binary/hex or octal
10, 171, 3004, 52429, 908766, x

Find the value of x

This one should give you a headache:
1621 2432 6448 x

Find the value of x and explain your reasoning.