hai every body... i still stuck until now for the following problem. hope somebody can guide me.

Question

A box contains 5 black cubes and 3 red cubes. Two cube are drawn at random from the box. find the probability that :

(a) both cubes are black

(b) both cubes are the same colour

(c) both cubes are different colours

ans given:

5/14, 13/18 ( i also confuse this ans for which question (a)/ (b) or (c)

My solution:

(a) P( both cubes are black ) = P (Black,Black)

= 5/8 * 5/8

= 25/64

(b) P (both cubes are the same colour) = P (Black,Black) + P (Red,Red)

= 25/64 + 3/8*3/8

= 25/64 + 9/64

= 34/64

= 17/32

Remarks: base on my calculation it look like it wrong when i compare it with the given ans..