$(1$ point$)$ You are given the four points in the plane $A=(4,-3),B=(6,2),C=(11,-1),$ and $D=(13,4).$ The graph of the function $f(x)$ consists of the three line segments $AB,BC$ and $CD.$ Find the integral ${\displaystyle \underset{4}{\overset{13}{}}}f(x)dx$ by interpreting the integral in terms of sums and$/$or differences of areas of elementary figures.

${\displaystyle \underset{4}{\overset{13}{}}}f(x)dx=$

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