Find the Y-Intercept of a Linear Function

Consider a linear function defined by the equation:

$$y = mx + b$$

where $m$ represents the slope and $b$ represents the y-intercept. A particular linear function has the property that when $x = 2$, $y = 5$, and when $x = 4$, the function produces an output of $y = 11$. Find the value of $b$ (the y-intercept of the function). Your final answer should be expressed as a decimal.