The intersection of lines $l$ and $m$ forms the 4 angles $\angle{A}$, $\angle{B}$, $\angle{C}$, and $\angle{D}$. The measure of $\angle{B}$ is $3\dfrac{1}{2}$ times the measure of $\angle{A}$. Which of the following values is closest to the measure of $\angle{A}$ ?

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The intersection of two lines will create two pairs of congruent angles. The four angles should add up to $360^\circ$.

$$2x+2y = 360$$

If one angle is $3\dfrac{1}{2}$ times the other:

$$x = 3\frac{1}{2}(y)$$ $$x= \frac{7}{2}y$$

After substituting:

$$2\left(\frac{7}{2}\right)y+2y = 360$$ $$7y+2y = 360$$ $$9y = 360$$ $$y= \boxed{40}$$