A dataset $X$ has $n=20$ observations with a mean of $\bar{x} = 50$ and a variance of $s^2 = 100$. If every observation $x_i$ is transformed into $y_i = a x_i + b$ such that the new dataset has a mean of $\bar{y} = 120$ and a variance of $s_y^2 = 225$, which of the following could be the transformation parameters $(a, b)$?