There are 44 cards which are not a K or Q
Thus the probability that the fiorst card is not a K or Q is 44/52
The probability that the second is not a K or Q is 43/51 (as after the first card is drawn there are 51 remaining of which 43 are not K or Q.
.. and so on for the third and fouth card.
The final probability is the product of the four probabilities you will have calculated.
After drawing 5 cards none of which are a K or Q, you have a deck with 47 cards of which 39 are not a K or Q.b) Given that a king or queen does not occur in the first 5 cards drawn, what is the probability that a king or queen occurs in 3 or fewer more draws?
The required probability here is 1 minus the probability that none of the first three cards is a K or Q. This klatter probability can be calculated using the technique of part (a).