Two coins are tossed simultaneously. One of them is a common currency and current, while the other coin favors the side of heads by a factor of 2/3. Consider the following variables, "U" is the total number of observed outcomes and "V" is a Bernoulli distribution that assumes the value 1 if both currencies are equal. Calculate the union of U and V and check if they are independent. Calculate the mean and variance of 2U - V