The task is to generate the correct answer for a given math problem.

[Q]: Problem: from a pack of cards , two cards are drawn one after the other , with replacement . what is the probability that the first card is a black card and the second card is a king ?
[A]: 1 / 26


[Q]: Problem: if 4 xz + yw = 10 and xw + yz = 20 , what is the value of the expression ( 2 x + y ) ( 2 z + w ) ?
[A]: 50 .


[Q]: Problem: if p ( a ) = 5 / 7 and p ( b ) = 2 / 5 , find p ( a n b ) if a and b are independent events .
[A]:
2 / 7