SAT math practice question: Straight line and intersections

 
Try the following SAT math practice question (Calculator Permitted, Grid in question) that tests your understanding of properties of straight lines in the coordinate plane.

Question: In the $xy-$plane, line $l$ has equation $y=\dfrac{1}{4}x+3$, and line $m$ has equation $y=\dfrac{1}{2}x+b$. If the lines intersect at the point with coordinates $\left(t, \dfrac{11}{2}\right)$, what is the value of $b$ ?