Let the mean and the variance of 5 observations $x_1, x_2, x_3, x_4, x_5$ be $\dfrac{24}{5}$ and $\dfrac{194}{25}$ respectively. If the mean and variance of the first 4 observations are $\dfrac{7}{2}$ and $a$ respectively, then $(4a + x_5)$ is equal to: