Optimization & Lagrange Multipliers · Medium problem

The line $y = mx + b$ is fitted to the points $(0, 1)$, $(1, 3)$, $(2, 4)$, $(3, 4)$ by least squares: $m$ and $b$ minimize $E(m, b) = \sum (y_i - m x_i - b)^2$. Find $m + b$.