Agroup of 50 mice is being used in an experiment. event a is a male mouse being chosen at random. event b is a mouse that is at least 6 months old being chosen. which expression describes a female mouse younger than 6 months old being chosen?

Given:
The group of 50 mice. 
Event A = A male mouse is being chosen at random.
Event B = A mouse that is at least 6 months old being chosen.

The expression that describes a female mouse younger than 6 months old being chosen:

[A-} * [B] = inverse of A * B