If the variance of a discrete random variable x is v (x) = 1.6, then v (2x + 3) is

Adding an offset to the data changes the mean, but not the variance. Multiplying the data by a constant changes the variance by the square of that constant.

v (a·x) = a²·v (x)

You will have v (2x+3) = 2²·v (x) = 4·1.6 = 6.4