The probability of occurance of two two events A and B are 1/4 and 1/2 respectively. The probability of their simultaneous occurrance is 7/50. Find the probability that neither A nor B occurs.

P ( neither A nor B) =  $PA and B$  

=   $PA\cap B$=   $PA\cup B$=  $1-PA\cup B$  

=  $1-\frac{61}{100}=\frac{39}{100}$