There are four blue marbles, an unknown number of red (r marbles, and six yellow marbles in a bag. which expression represents the probability of randomly selecting a blue marble, replacing it, and then randomly selecting a red marble?

There are a total of  marbles in the bag

The probability of choosing a blue is 

The probability of choosing a red is 

The probability of choosing a blue, replacing it, and then a red is
× = 

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.