Matrices And Determinants

Consider the matrices : $$A=\left[\begin{array}{cc}2 & -5 \\ 3 & m\end{array}\right], B=\left[\begin{array}{l}20 \\ m\end{array}\right]$$ and $$X=\left[\begin{array}{l}x \\ y\end{array}\right]$$. Let the set of all \(m\), for which the system of equations \(A X=B\) has a negative solution (i.e., \(x<0\) and \(y<0\)), be the interval \((a, b)\). Then \(8 \int_\limits a^b|A| d m\) is equal to _________.