Fill in the Remaining Information and Compute the Estimated Value

Essay

Fill in the remaining information and compute the estimated value of b.
$$X _ { t } - \bar { X } \quad Y _ { t } - \bar { Y } \quad \left( X _ { t } - \bar { X } \right) \left( X _ { t } - \bar { X } \right) \quad \left( X _ { t } - \bar { X } \right) ^ { 2 }$$

$\begin{array} { l l l } (t)&(X)&(Y)\\1 & 10 & 35 \\ 2 & 15 & 45 \\ 3 & 12 & 40 \\ 4 & 20 & 50 \end{array}$